Subsequent data information for small data transmission

ABSTRACT

A base station central unit receives, from a base station distributed unit, assistance information comprising information of subsequent data for a small data transmission procedure of a wireless device. Based on the assistance information, the base station central unit sends, to the wireless device, a radio resource control release message or a radio resource control message indicating transition to a radio resource control connected state.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/US2021/048467, filed Aug. 31, 2021, which claims the benefit of U.S.Provisional Application No. 63/072,751, filed Aug. 31, 2020, all ofwhich are hereby incorporated by reference in its entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of several of the various embodiments of the present disclosureare described herein with reference to the drawings.

FIG. 1A and FIG. 1B illustrate example mobile communication networks inwhich embodiments of the present disclosure may be implemented.

FIG. 2A and FIG. 2B respectively illustrate a New Radio (NR) user planeand control plane protocol stack.

FIG. 3 illustrates an example of services provided between protocollayers of the NR user plane protocol stack of FIG. 2A.

FIG. 4A illustrates an example downlink data flow through the NR userplane protocol stack of FIG. 2A.

FIG. 4B illustrates an example format of a MAC subheader in a MAC PDU.

FIG. 5A and FIG. 5B respectively illustrate a mapping between logicalchannels, transport channels, and physical channels for the downlink anduplink.

FIG. 6 is an example diagram showing RRC state transitions of a UE.

FIG. 7 illustrates an example configuration of an NR frame into whichOFDM symbols are grouped.

FIG. 8 illustrates an example configuration of a slot in the time andfrequency domain for an NR carrier.

FIG. 9 illustrates an example of bandwidth adaptation using threeconfigured BWPs for an NR carrier.

FIG. 10A illustrates three carrier aggregation configurations with twocomponent carriers.

FIG. 10B illustrates an example of how aggregated cells may beconfigured into one or more PUCCH groups.

FIG. 11A illustrates an example of an SS/PBCH block structure andlocation.

FIG. 11B illustrates an example of CSI-RSs that are mapped in the timeand frequency domains.

FIG. 12A and FIG. 12B respectively illustrate examples of three downlinkand uplink beam management procedures.

FIG. 13A, FIG. 13B, and FIG. 13C respectively illustrate a four-stepcontention-based random access procedure, a two-step contention-freerandom access procedure, and another two-step random access procedure.

FIG. 14A illustrates an example of CORESET configurations for abandwidth part.

FIG. 14B illustrates an example of a CCE-to-REG mapping for DCItransmission on a CORESET and PDCCH processing.

FIG. 15 illustrates an example of a wireless device in communicationwith a base station.

FIG. 16A, FIG. 16B, FIG. 16C, and FIG. 16D illustrate example structuresfor uplink and downlink transmission.

FIG. 17 is a diagram of an aspect of an example embodiment of thepresent disclosure.

FIG. 18 is a diagram of an aspect of an example embodiment of thepresent disclosure.

FIG. 19 is a diagram of an aspect of an example embodiment of thepresent disclosure.

FIG. 20 is a diagram of an aspect of an example embodiment of thepresent disclosure.

FIG. 21 is a diagram of an aspect of an example embodiment of thepresent disclosure.

FIG. 22 is a diagram of an aspect of an example embodiment of thepresent disclosure.

FIG. 23 is a diagram of an aspect of an example embodiment of thepresent disclosure.

FIG. 24 is a diagram of an aspect of an example embodiment of thepresent disclosure.

FIG. 25 is a diagram of an aspect of an example embodiment of thepresent disclosure.

FIG. 26 is a diagram of an aspect of an example embodiment of thepresent disclosure.

FIG. 27 is a diagram of an aspect of an example embodiment of thepresent disclosure.

FIG. 28 is a diagram of an aspect of an example embodiment of thepresent disclosure.

FIG. 29 is a diagram of an aspect of an example embodiment of thepresent disclosure.

FIG. 30 is a diagram of an aspect of an example embodiment of thepresent disclosure.

FIG. 31 is a diagram of an aspect of an example embodiment of thepresent disclosure.

DETAILED DESCRIPTION

In the present disclosure, various embodiments are presented as examplesof how the disclosed techniques may be implemented and/or how thedisclosed techniques may be practiced in environments and scenarios. Itwill be apparent to persons skilled in the relevant art that variouschanges in form and detail can be made therein without departing fromthe scope. In fact, after reading the description, it will be apparentto one skilled in the relevant art how to implement alternativeembodiments. The present embodiments should not be limited by any of thedescribed exemplary embodiments. The embodiments of the presentdisclosure will be described with reference to the accompanyingdrawings. Limitations, features, and/or elements from the disclosedexample embodiments may be combined to create further embodiments withinthe scope of the disclosure. Any figures which highlight thefunctionality and advantages, are presented for example purposes only.The disclosed architecture is sufficiently flexible and configurable,such that it may be utilized in ways other than that shown. For example,the actions listed in any flowchart may be re-ordered or only optionallyused in some embodiments.

Embodiments may be configured to operate as needed. The disclosedmechanism may be performed when certain criteria are met, for example,in a wireless device, a base station, a radio environment, a network, acombination of the above, and/or the like. Example criteria may bebased, at least in part, on for example, wireless device or network nodeconfigurations, traffic load, initial system set up, packet sizes,traffic characteristics, a combination of the above, and/or the like.When the one or more criteria are met, various example embodiments maybe applied. Therefore, it may be possible to implement exampleembodiments that selectively implement disclosed protocols.

A base station may communicate with a mix of wireless devices. Wirelessdevices and/or base stations may support multiple technologies, and/ormultiple releases of the same technology. Wireless devices may have somespecific capability(ies) depending on wireless device category and/orcapability(ies). When this disclosure refers to a base stationcommunicating with a plurality of wireless devices, this disclosure mayrefer to a subset of the total wireless devices in a coverage area. Thisdisclosure may refer to, for example, a plurality of wireless devices ofa given LTE or 5G release with a given capability and in a given sectorof the base station. The plurality of wireless devices in thisdisclosure may refer to a selected plurality of wireless devices, and/ora subset of total wireless devices in a coverage area which performaccording to disclosed methods, and/or the like. There may be aplurality of base stations or a plurality of wireless devices in acoverage area that may not comply with the disclosed methods, forexample, those wireless devices or base stations may perform based onolder releases of LTE or 5G technology.

In this disclosure, “a” and “an” and similar phrases are to beinterpreted as “at least one” and “one or more.” Similarly, any termthat ends with the suffix “(s)” is to be interpreted as “at least one”and “one or more.” In this disclosure, the term “may” is to beinterpreted as “may, for example.” In other words, the term “may” isindicative that the phrase following the term “may” is an example of oneof a multitude of suitable possibilities that may, or may not, beemployed by one or more of the various embodiments. The terms“comprises” and “consists of”, as used herein, enumerate one or morecomponents of the element being described. The term “comprises” isinterchangeable with “includes” and does not exclude unenumeratedcomponents from being included in the element being described. Bycontrast, “consists of” provides a complete enumeration of the one ormore components of the element being described. The term “based on”, asused herein, should be interpreted as “based at least in part on” ratherthan, for example, “based solely on”. The term “and/or” as used hereinrepresents any possible combination of enumerated elements. For example,“A, B, and/or C” may represent A; B; C; A and B; A and C; B and C; or A,B, and C.

If A and B are sets and every element of A is an element of B, A iscalled a subset of B. In this specification, only non-empty sets andsubsets are considered. For example, possible subsets of B={cell1,cell2} are: {cell1}, {cell2}, and {cell1, cell2}. The phrase “based on”(or equally “based at least on”) is indicative that the phrase followingthe term “based on” is an example of one of a multitude of suitablepossibilities that may, or may not, be employed to one or more of thevarious embodiments. The phrase “in response to” (or equally “inresponse at least to”) is indicative that the phrase following thephrase “in response to” is an example of one of a multitude of suitablepossibilities that may, or may not, be employed to one or more of thevarious embodiments. The phrase “depending on” (or equally “depending atleast to”) is indicative that the phrase following the phrase “dependingon” is an example of one of a multitude of suitable possibilities thatmay, or may not, be employed to one or more of the various embodiments.The phrase “employing/using” (or equally “employing/using at least”) isindicative that the phrase following the phrase “employing/using” is anexample of one of a multitude of suitable possibilities that may, or maynot, be employed to one or more of the various embodiments.

The term configured may relate to the capacity of a device whether thedevice is in an operational or non-operational state. Configured mayrefer to specific settings in a device that effect the operationalcharacteristics of the device whether the device is in an operational ornon-operational state. In other words, the hardware, software, firmware,registers, memory values, and/or the like may be “configured” within adevice, whether the device is in an operational or nonoperational state,to provide the device with specific characteristics. Terms such as “acontrol message to cause in a device” may mean that a control messagehas parameters that may be used to configure specific characteristics ormay be used to implement certain actions in the device, whether thedevice is in an operational or non-operational state.

In this disclosure, parameters (or equally called, fields, orInformation elements: IEs) may comprise one or more information objects,and an information object may comprise one or more other objects. Forexample, if parameter (IE) N comprises parameter (IE) M, and parameter(IE) M comprises parameter (IE) K, and parameter (IE) K comprisesparameter (information element) J. Then, for example, N comprises K, andN comprises J. In an example embodiment, when one or more messagescomprise a plurality of parameters, it implies that a parameter in theplurality of parameters is in at least one of the one or more messages,but does not have to be in each of the one or more messages.

Many features presented are described as being optional through the useof “may” or the use of parentheses. For the sake of brevity andlegibility, the present disclosure does not explicitly recite each andevery permutation that may be obtained by choosing from the set ofoptional features. The present disclosure is to be interpreted asexplicitly disclosing all such permutations. For example, a systemdescribed as having three optional features may be embodied in sevenways, namely with just one of the three possible features, with any twoof the three possible features or with three of the three possiblefeatures.

Many of the elements described in the disclosed embodiments may beimplemented as modules. A module is defined here as an element thatperforms a defined function and has a defined interface to otherelements. The modules described in this disclosure may be implemented inhardware, software in combination with hardware, firmware, wetware (e.g.hardware with a biological element) or a combination thereof, which maybe behaviorally equivalent. For example, modules may be implemented as asoftware routine written in a computer language configured to beexecuted by a hardware machine (such as C, C++, Fortran, Java, Basic,Matlab or the like) or a modeling/simulation program such as Simulink,Stateflow, GNU Octave, or Lab VIEWMathScript. It may be possible toimplement modules using physical hardware that incorporates discrete orprogrammable analog, digital and/or quantum hardware. Examples ofprogrammable hardware comprise: computers, microcontrollers,microprocessors, application-specific integrated circuits (ASICs); fieldprogrammable gate arrays (FPGAs); and complex programmable logic devices(CPLDs). Computers, microcontrollers and microprocessors are programmedusing languages such as assembly, C, C++ or the like. FPGAs, ASICs andCPLDs are often programmed using hardware description languages (HDL)such as VHSIC hardware description language (VHDL) or Verilog thatconfigure connections between internal hardware modules with lesserfunctionality on a programmable device. The mentioned technologies areoften used in combination to achieve the result of a functional module.

FIG. 1A illustrates an example of a mobile communication network 100 inwhich embodiments of the present disclosure may be implemented. Themobile communication network 100 may be, for example, a public landmobile network (PLMN) run by a network operator. As illustrated in FIG.1A, the mobile communication network 100 includes a core network (CN)102, a radio access network (RAN) 104, and a wireless device 106.

The CN 102 may provide the wireless device 106 with an interface to oneor more data networks (DNs), such as public DNs (e.g., the Internet),private DNs, and/or intra-operator DNs. As part of the interfacefunctionality, the CN 102 may set up end-to-end connections between thewireless device 106 and the one or more DNs, authenticate the wirelessdevice 106, and provide charging functionality.

The RAN 104 may connect the CN 102 to the wireless device 106 throughradio communications over an air interface. As part of the radiocommunications, the RAN 104 may provide scheduling, radio resourcemanagement, and retransmission protocols. The communication directionfrom the RAN 104 to the wireless device 106 over the air interface isknown as the downlink and the communication direction from the wirelessdevice 106 to the RAN 104 over the air interface is known as the uplink.Downlink transmissions may be separated from uplink transmissions usingfrequency division duplexing (FDD), time-division duplexing (TDD),and/or some combination of the two duplexing techniques.

The term wireless device may be used throughout this disclosure to referto and encompass any mobile device or fixed (non-mobile) device forwhich wireless communication is needed or usable. For example, awireless device may be a telephone, smart phone, tablet, computer,laptop, sensor, meter, wearable device, Internet of Things (IoT) device,vehicle road side unit (RSU), relay node, automobile, and/or anycombination thereof. The term wireless device encompasses otherterminology, including user equipment (UE), user terminal (UT), accessterminal (AT), mobile station, handset, wireless transmit and receiveunit (WTRU), and/or wireless communication device.

The RAN 104 may include one or more base stations (not shown). The termbase station may be used throughout this disclosure to refer to andencompass a Node B (associated with UMTS and/or 3G standards), anEvolved Node B (eNB, associated with E-UTRA and/or 4G standards), aremote radio head (RRH), a baseband processing unit coupled to one ormore RRHs, a repeater node or relay node used to extend the coveragearea of a donor node, a Next Generation Evolved Node B (ng-eNB), aGeneration Node B (gNB, associated with NR and/or 5G standards), anaccess point (AP, associated with, for example, WiFi or any othersuitable wireless communication standard), and/or any combinationthereof. A base station may comprise at least one gNB Central Unit(gNB-CU) and at least one a gNB Distributed Unit (gNB-DU).

A base station included in the RAN 104 may include one or more sets ofantennas for communicating with the wireless device 106 over the airinterface. For example, one or more of the base stations may includethree sets of antennas to respectively control three cells (or sectors).The size of a cell may be determined by a range at which a receiver(e.g., a base station receiver) can successfully receive thetransmissions from a transmitter (e.g., a wireless device transmitter)operating in the cell. Together, the cells of the base stations mayprovide radio coverage to the wireless device 106 over a wide geographicarea to support wireless device mobility.

In addition to three-sector sites, other implementations of basestations are possible. For example, one or more of the base stations inthe RAN 104 may be implemented as a sectored site with more or less thanthree sectors. One or more of the base stations in the RAN 104 may beimplemented as an access point, as a baseband processing unit coupled toseveral remote radio heads (RRHs), and/or as a repeater or relay nodeused to extend the coverage area of a donor node. A baseband processingunit coupled to RRHs may be part of a centralized or cloud RANarchitecture, where the baseband processing unit may be eithercentralized in a pool of baseband processing units or virtualized. Arepeater node may amplify and rebroadcast a radio signal received from adonor node. A relay node may perform the same/similar functions as arepeater node but may decode the radio signal received from the donornode to remove noise before amplifying and rebroadcasting the radiosignal.

The RAN 104 may be deployed as a homogenous network of macrocell basestations that have similar antenna patterns and similar high-leveltransmit powers. The RAN 104 may be deployed as a heterogeneous network.In heterogeneous networks, small cell base stations may be used toprovide small coverage areas, for example, coverage areas that overlapwith the comparatively larger coverage areas provided by macrocell basestations. The small coverage areas may be provided in areas with highdata traffic (or so-called “hotspots”) or in areas with weak macrocellcoverage. Examples of small cell base stations include, in order ofdecreasing coverage area, microcell base stations, picocell basestations, and femtocell base stations or home base stations.

The Third-Generation Partnership Project (3GPP) was formed in 1998 toprovide global standardization of specifications for mobilecommunication networks similar to the mobile communication network 100in FIG. 1A. To date, 3GPP has produced specifications for threegenerations of mobile networks: a third generation (3G) network known asUniversal Mobile Telecommunications System (UMTS), a fourth generation(4G) network known as Long-Term Evolution (LTE), and a fifth generation(5G) network known as 5G System (5GS). Embodiments of the presentdisclosure are described with reference to the RAN of a 3GPP 5G network,referred to as next-generation RAN (NG-RAN). Embodiments may beapplicable to RANs of other mobile communication networks, such as theRAN 104 in FIG. 1A, the RANs of earlier 3G and 4G networks, and those offuture networks yet to be specified (e.g., a 3GPP 6G network). NG-RANimplements 5G radio access technology known as New Radio (NR) and may beprovisioned to implement 4G radio access technology or other radioaccess technologies, including non-3GPP radio access technologies.

FIG. 1B illustrates another example mobile communication network 150 inwhich embodiments of the present disclosure may be implemented. Mobilecommunication network 150 may be, for example, a PLMN run by a networkoperator. As illustrated in FIG. 1B, mobile communication network 150includes a 5G core network (5G-CN) 152, an NG-RAN 154, and UEs 156A and156B (collectively UEs 156). These components may be implemented andoperate in the same or similar manner as corresponding componentsdescribed with respect to FIG. 1A.

The 5G-CN 152 provides the UEs 156 with an interface to one or more DNs,such as public DNs (e.g., the Internet), private DNs, and/orintra-operator DNs. As part of the interface functionality, the 5G-CN152 may set up end-to-end connections between the UEs 156 and the one ormore DNs, authenticate the UEs 156, and provide charging functionality.Compared to the CN of a 3GPP 4G network, the basis of the 5G-CN 152 maybe a service-based architecture. This means that the architecture of thenodes making up the 5G-CN 152 may be defined as network functions thatoffer services via interfaces to other network functions. The networkfunctions of the 5G-CN 152 may be implemented in several ways, includingas network elements on dedicated or shared hardware, as softwareinstances running on dedicated or shared hardware, or as virtualizedfunctions instantiated on a platform (e.g., a cloud-based platform).

As illustrated in FIG. 1B, the 5G-CN 152 includes an Access and MobilityManagement Function (AMF) 158A and a User Plane Function (UPF) 158B,which are shown as one component AMF/UPF 158 in FIG. 1B for ease ofillustration. The UPF 158B may serve as a gateway between the NG-RAN 154and the one or more DNs. The UPF 158B may perform functions such aspacket routing and forwarding, packet inspection and user plane policyrule enforcement, traffic usage reporting, uplink classification tosupport routing of traffic flows to the one or more DNs, quality ofservice (QoS) handling for the user plane (e.g., packet filtering,gating, uplink/downlink rate enforcement, and uplink trafficverification), downlink packet buffering, and downlink data notificationtriggering. The UPF 158B may serve as an anchor point forintra-/inter-Radio Access Technology (RAT) mobility, an externalprotocol (or packet) data unit (PDU) session point of interconnect tothe one or more DNs, and/or a branching point to support a multi-homedPDU session. The UEs 156 may be configured to receive services through aPDU session, which is a logical connection between a UE and a DN.

The AMF 158A may perform functions such as Non-Access Stratum (NAS)signaling termination, NAS signaling security, Access Stratum (AS)security control, inter-CN node signaling for mobility between 3GPPaccess networks, idle mode UE reachability (e.g., control and executionof paging retransmission), registration area management, intra-systemand inter-system mobility support, access authentication, accessauthorization including checking of roaming rights, mobility managementcontrol (subscription and policies), network slicing support, and/orsession management function (SMF) selection. NAS may refer to thefunctionality operating between a CN and a UE, and AS may refer to thefunctionality operating between the UE and a RAN.

The 5G-CN 152 may include one or more additional network functions thatare not shown in FIG. 1B for the sake of clarity. For example, the 5G-CN152 may include one or more of a Session Management Function (SMF), anNR Repository Function (NRF), a Policy Control Function (PCF), a NetworkExposure Function (NEF), a Unified Data Management (UDM), an ApplicationFunction (AF), and/or an Authentication Server Function (AUSF).

The NG-RAN 154 may connect the 5G-CN 152 to the UEs 156 through radiocommunications over the air interface. The NG-RAN 154 may include one ormore gNBs, illustrated as gNB 160A and gNB 160B (collectively gNBs 160)and/or one or more ng-eNB s, illustrated as ng-eNB 162A and ng-eNB 162B(collectively ng-eNB s 162). The gNBs 160 and ng-eNBs 162 may be moregenerically referred to as base stations. The gNBs 160 and ng-eNB s 162may include one or more sets of antennas for communicating with the UEs156 over an air interface. For example, one or more of the gNBs 160and/or one or more of the ng-eNBs 162 may include three sets of antennasto respectively control three cells (or sectors). Together, the cells ofthe gNBs 160 and the ng-eNBs 162 may provide radio coverage to the UEs156 over a wide geographic area to support UE mobility.

As shown in FIG. 1B, the gNBs 160 and/or the ng-eNB s 162 may beconnected to the 5G-CN 152 by means of an NG interface and to other basestations by an Xn interface. The NG and Xn interfaces may be establishedusing direct physical connections and/or indirect connections over anunderlying transport network, such as an internet protocol (IP)transport network. The gNBs 160 and/or the ng-eNB s 162 may be connectedto the UEs 156 by means of a Uu interface. For example, as illustratedin FIG. 1B, gNB 160A may be connected to the UE 156A by means of a Uuinterface. The NG, Xn, and Uu interfaces are associated with a protocolstack. The protocol stacks associated with the interfaces may be used bythe network elements in FIG. 1B to exchange data and signaling messagesand may include two planes: a user plane and a control plane. The userplane may handle data of interest to a user. The control plane mayhandle signaling messages of interest to the network elements.

The gNBs 160 and/or the ng-eNB s 162 may be connected to one or moreAMF/UPF functions of the 5G-CN 152, such as the AMF/UPF 158, by means ofone or more NG interfaces. For example, the gNB 160A may be connected tothe UPF 158B of the AMF/UPF 158 by means of an NG-User plane (NG-U)interface. The NG-U interface may provide delivery (e.g., non-guaranteeddelivery) of user plane PDUs between the gNB 160A and the UPF 158B. ThegNB 160A may be connected to the AMF 158A by means of an NG-Controlplane (NG-C) interface. The NG-C interface may provide, for example, NGinterface management, UE context management, UE mobility management,transport of NAS messages, paging, PDU session management, andconfiguration transfer and/or warning message transmission.

The gNBs 160 may provide NR user plane and control plane protocolterminations towards the UEs 156 over the Uu interface. For example, thegNB 160A may provide NR user plane and control plane protocolterminations toward the UE 156A over a Uu interface associated with afirst protocol stack. The ng-eNBs 162 may provide Evolved UMTSTerrestrial Radio Access (E-UTRA) user plane and control plane protocolterminations towards the UEs 156 over a Uu interface, where E-UTRArefers to the 3GPP 4G radio-access technology. For example, the ng-eNB162B may provide E-UTRA user plane and control plane protocolterminations towards the UE 156B over a Uu interface associated with asecond protocol stack.

The 5G-CN 152 was described as being configured to handle NR and 4Gradio accesses. It will be appreciated by one of ordinary skill in theart that it may be possible for NR to connect to a 4G core network in amode known as “non-standalone operation.” In non-standalone operation, a4G core network is used to provide (or at least support) control-planefunctionality (e.g., initial access, mobility, and paging). Althoughonly one AMF/UPF 158 is shown in FIG. 1B, one gNB or ng-eNB may beconnected to multiple AMF/UPF nodes to provide redundancy and/or to loadshare across the multiple AMF/UPF nodes.

As discussed, an interface (e.g., Uu, Xn, and NG interfaces) between thenetwork elements in FIG. 1B may be associated with a protocol stack thatthe network elements use to exchange data and signaling messages. Aprotocol stack may include two planes: a user plane and a control plane.The user plane may handle data of interest to a user, and the controlplane may handle signaling messages of interest to the network elements.

FIG. 2A and FIG. 2B respectively illustrate examples of NR user planeand NR control plane protocol stacks for the Uu interface that liesbetween a UE 210 and a gNB 220. The protocol stacks illustrated in FIG.2A and FIG. 2B may be the same or similar to those used for the Uuinterface between, for example, the UE 156A and the gNB 160A shown inFIG. 1B.

FIG. 2A illustrates a NR user plane protocol stack comprising fivelayers implemented in the UE 210 and the gNB 220. At the bottom of theprotocol stack, physical layers (PHYs) 211 and 221 may provide transportservices to the higher layers of the protocol stack and may correspondto layer 1 of the Open Systems Interconnection (OSI) model. The nextfour protocols above PHYs 211 and 221 comprise media access controllayers (MACs) 212 and 222, radio link control layers (RLCs) 213 and 223,packet data convergence protocol layers (PDCPs) 214 and 224, and servicedata application protocol layers (SDAPs) 215 and 225. Together, thesefour protocols may make up layer 2, or the data link layer, of the OSImodel.

FIG. 3 illustrates an example of services provided between protocollayers of the NR user plane protocol stack. Starting from the top ofFIG. 2A and FIG. 3 , the SDAPs 215 and 225 may perform QoS flowhandling. The UE 210 may receive services through a PDU session, whichmay be a logical connection between the UE 210 and a DN. The PDU sessionmay have one or more QoS flows. A UPF of a CN (e.g., the UPF 158B) maymap IP packets to the one or more QoS flows of the PDU session based onQoS requirements (e.g., in terms of delay, data rate, and/or errorrate). The SDAPs 215 and 225 may perform mapping/de-mapping between theone or more QoS flows and one or more data radio bearers. Themapping/de-mapping between the QoS flows and the data radio bearers maybe determined by the SDAP 225 at the gNB 220. The SDAP 215 at the UE 210may be informed of the mapping between the QoS flows and the data radiobearers through reflective mapping or control signaling received fromthe gNB 220. For reflective mapping, the SDAP 225 at the gNB 220 maymark the downlink packets with a QoS flow indicator (QFI), which may beobserved by the SDAP 215 at the UE 210 to determine themapping/de-mapping between the QoS flows and the data radio bearers.

The PDCPs 214 and 224 may perform header compression/decompression toreduce the amount of data that needs to be transmitted over the airinterface, ciphering/deciphering to prevent unauthorized decoding ofdata transmitted over the air interface, and integrity protection (toensure control messages originate from intended sources. The PDCPs 214and 224 may perform retransmissions of undelivered packets, in-sequencedelivery and reordering of packets, and removal of packets received induplicate due to, for example, an intra-gNB handover. The PDCPs 214 and224 may perform packet duplication to improve the likelihood of thepacket being received and, at the receiver, remove any duplicatepackets. Packet duplication may be useful for services that require highreliability.

Although not shown in FIG. 3 , PDCPs 214 and 224 may performmapping/de-mapping between a split radio bearer and RLC channels in adual connectivity scenario. Dual connectivity is a technique that allowsa UE to connect to two cells or, more generally, two cell groups: amaster cell group (MCG) and a secondary cell group (SCG). A split beareris when a single radio bearer, such as one of the radio bearers providedby the PDCPs 214 and 224 as a service to the SDAPs 215 and 225, ishandled by cell groups in dual connectivity. The PDCPs 214 and 224 maymap/de-map the split radio bearer between RLC channels belonging to cellgroups.

The RLCs 213 and 223 may perform segmentation, retransmission throughAutomatic Repeat Request (ARQ), and removal of duplicate data unitsreceived from MACs 212 and 222, respectively. The RLCs 213 and 223 maysupport three transmission modes: transparent mode (TM); unacknowledgedmode (UM); and acknowledged mode (AM). Based on the transmission mode anRLC is operating, the RLC may perform one or more of the notedfunctions. The RLC configuration may be per logical channel with nodependency on numerologies and/or Transmission Time Interval (TTI)durations. As shown in FIG. 3 , the RLCs 213 and 223 may provide RLCchannels as a service to PDCPs 214 and 224, respectively.

The MACs 212 and 222 may perform multiplexing/demultiplexing of logicalchannels and/or mapping between logical channels and transport channels.The multiplexing/demultiplexing may include multiplexing/demultiplexingof data units, belonging to the one or more logical channels, into/fromTransport Blocks (TBs) delivered to/from the PHYs 211 and 221. The MAC222 may be configured to perform scheduling, scheduling informationreporting, and priority handling between UEs by means of dynamicscheduling. Scheduling may be performed in the gNB 220 (at the MAC 222)for downlink and uplink. The MACs 212 and 222 may be configured toperform error correction through Hybrid Automatic Repeat Request (HARQ)(e.g., one HARQ entity per carrier in case of Carrier Aggregation (CA)),priority handling between logical channels of the UE 210 by means oflogical channel prioritization, and/or padding. The MACs 212 and 222 maysupport one or more numerologies and/or transmission timings. In anexample, mapping restrictions in a logical channel prioritization maycontrol which numerology and/or transmission timing a logical channelmay use. As shown in FIG. 3 , the MACs 212 and 222 may provide logicalchannels as a service to the RLCs 213 and 223.

The PHYs 211 and 221 may perform mapping of transport channels tophysical channels and digital and analog signal processing functions forsending and receiving information over the air interface. These digitaland analog signal processing functions may include, for example,coding/decoding and modulation/demodulation. The PHYs 211 and 221 mayperform multi-antenna mapping. As shown in FIG. 3 , the PHYs 211 and 221may provide one or more transport channels as a service to the MACs 212and 222.

FIG. 4A illustrates an example downlink data flow through the NR userplane protocol stack. FIG. 4A illustrates a downlink data flow of threeIP packets (n, n+1, and m) through the NR user plane protocol stack togenerate two TBs at the gNB 220. An uplink data flow through the NR userplane protocol stack may be similar to the downlink data flow depictedin FIG. 4A.

The downlink data flow of FIG. 4A begins when SDAP 225 receives thethree IP packets from one or more QoS flows and maps the three packetsto radio bearers. In FIG. 4A, the SDAP 225 maps IP packets n and n+1 toa first radio bearer 402 and maps IP packet m to a second radio bearer404. An SDAP header (labeled with an “H” in FIG. 4A) is added to an IPpacket. The data unit from/to a higher protocol layer is referred to asa service data unit (SDU) of the lower protocol layer and the data unitto/from a lower protocol layer is referred to as a protocol data unit(PDU) of the higher protocol layer. As shown in FIG. 4A, the data unitfrom the SDAP 225 is an SDU of lower protocol layer PDCP 224 and is aPDU of the SDAP 225.

The remaining protocol layers in FIG. 4A may perform their associatedfunctionality (e.g., with respect to FIG. 3 ), add correspondingheaders, and forward their respective outputs to the next lower layer.For example, the PDCP 224 may perform IP-header compression andciphering and forward its output to the RLC 223. The RLC 223 mayoptionally perform segmentation (e.g., as shown for IP packet m in FIG.4A) and forward its output to the MAC 222. The MAC 222 may multiplex anumber of RLC PDUs and may attach a MAC subheader to an RLC PDU to forma transport block. In NR, the MAC subheaders may be distributed acrossthe MAC PDU, as illustrated in FIG. 4A. In LTE, the MAC subheaders maybe entirely located at the beginning of the MAC PDU. The NR MAC PDUstructure may reduce processing time and associated latency because theMAC PDU subheaders may be computed before the full MAC PDU is assembled.

FIG. 4B illustrates an example format of a MAC subheader in a MAC PDU.The MAC subheader includes: an SDU length field for indicating thelength (e.g., in bytes) of the MAC SDU to which the MAC subheadercorresponds; a logical channel identifier (LCID) field for identifyingthe logical channel from which the MAC SDU originated to aid in thedemultiplexing process; a flag (F) for indicating the size of the SDUlength field; and a reserved bit (R) field for future use.

FIG. 4B further illustrates MAC control elements (CEs) inserted into theMAC PDU by a MAC, such as MAC 223 or MAC 222. For example, FIG. 4Billustrates two MAC CEs inserted into the MAC PDU. MAC CEs may beinserted at the beginning of a MAC PDU for downlink transmissions (asshown in FIG. 4B) and at the end of a MAC PDU for uplink transmissions.MAC CEs may be used for in-band control signaling. Example MAC CEsinclude: scheduling-related MAC CEs, such as buffer status reports andpower headroom reports; activation/deactivation MAC CEs, such as thosefor activation/deactivation of PDCP duplication detection, channel stateinformation (CSI) reporting, sounding reference signal (SRS)transmission, and prior configured components; discontinuous reception(DRX) related MAC CEs; timing advance MAC CEs; and random access relatedMAC CEs. A MAC CE may be preceded by a MAC subheader with a similarformat as described for MAC SDUs and may be identified with a reservedvalue in the LCID field that indicates the type of control informationincluded in the MAC CE.

Before describing the NR control plane protocol stack, logical channels,transport channels, and physical channels are first described as well asa mapping between the channel types. One or more of the channels may beused to carry out functions associated with the NR control planeprotocol stack described later below.

FIG. 5A and FIG. 5B illustrate, for downlink and uplink respectively, amapping between logical channels, transport channels, and physicalchannels. Information is passed through channels between the RLC, theMAC, and the PHY of the NR protocol stack. A logical channel may be usedbetween the RLC and the MAC and may be classified as a control channelthat carries control and configuration information in the NR controlplane or as a traffic channel that carries data in the NR user plane. Alogical channel may be classified as a dedicated logical channel that isdedicated to a specific UE or as a common logical channel that may beused by more than one UE. A logical channel may also be defined by thetype of information it carries. The set of logical channels defined byNR include, for example:

-   -   a paging control channel (PCCH) for carrying paging messages        used to page a UE whose location is not known to the network on        a cell level;    -   a broadcast control channel (BCCH) for carrying system        information messages in the form of a master information block        (MIB) and several system information blocks (SIBs), wherein the        system information messages may be used by the UEs to obtain        information about how a cell is configured and how to operate        within the cell;    -   a common control channel (CCCH) for carrying control messages        together with random access;    -   a dedicated control channel (DCCH) for carrying control messages        to/from a specific the UE to configure the UE; and    -   a dedicated traffic channel (DTCH) for carrying user data        to/from a specific the UE.

Transport channels are used between the MAC and PHY layers and may bedefined by how the information they carry is transmitted over the airinterface. The set of transport channels defined by NR include, forexample:

-   -   a paging channel (PCH) for carrying paging messages that        originated from the PCCH;    -   a broadcast channel (BCH) for carrying the MIB from the BCCH;    -   a downlink shared channel (DL-SCH) for carrying downlink data        and signaling messages, including the SIBs from the BCCH;    -   an uplink shared channel (UL-SCH) for carrying uplink data and        signaling messages; and    -   a random access channel (RACH) for allowing a UE to contact the        network without any prior scheduling.

The PHY may use physical channels to pass information between processinglevels of the PHY. A physical channel may have an associated set oftime-frequency resources for carrying the information of one or moretransport channels. The PHY may generate control information to supportthe low-level operation of the PHY and provide the control informationto the lower levels of the PHY via physical control channels, known asL1/L2 control channels. The set of physical channels and physicalcontrol channels defined by NR include, for example:

-   -   a physical broadcast channel (PBCH) for carrying the MIB from        the BCH;    -   a physical downlink shared channel (PDSCH) for carrying downlink        data and signaling messages from the DL-SCH, as well as paging        messages from the PCH;    -   a physical downlink control channel (PDCCH) for carrying        downlink control information (DCI), which may include downlink        scheduling commands, uplink scheduling grants, and uplink power        control commands;    -   a physical uplink shared channel (PUSCH) for carrying uplink        data and signaling messages from the UL-SCH and in some        instances uplink control information (UCI) as described below;    -   a physical uplink control channel (PUCCH) for carrying UCI,        which may include HARQ acknowledgments, channel quality        indicators (CQI), pre-coding matrix indicators (PMI), rank        indicators (RI), and scheduling requests (SR); and    -   a physical random access channel (PRACH) for random access.

Similar to the physical control channels, the physical layer generatesphysical signals to support the low-level operation of the physicallayer. As shown in FIG. 5A and FIG. 5B, the physical layer signalsdefined by NR include: primary synchronization signals (PSS), secondarysynchronization signals (SSS), channel state information referencesignals (CSI-RS), demodulation reference signals (DMRS), soundingreference signals (SRS), and phase-tracking reference signals (PT-RS).These physical layer signals will be described in greater detail below.

FIG. 2B illustrates an example NR control plane protocol stack. As shownin FIG. 2B, the NR control plane protocol stack may use the same/similarfirst four protocol layers as the example NR user plane protocol stack.These four protocol layers include the PHYs 211 and 221, the MACs 212and 222, the RLCs 213 and 223, and the PDCPs 214 and 224. Instead ofhaving the SDAPs 215 and 225 at the top of the stack as in the NR userplane protocol stack, the NR control plane stack has radio resourcecontrols (RRCs) 216 and 226 and NAS protocols 217 and 237 at the top ofthe NR control plane protocol stack.

The NAS protocols 217 and 237 may provide control plane functionalitybetween the UE 210 and the AMF 230 (e.g., the AMF 158A) or, moregenerally, between the UE 210 and the CN. The NAS protocols 217 and 237may provide control plane functionality between the UE 210 and the AMF230 via signaling messages, referred to as NAS messages. There is nodirect path between the UE 210 and the AMF 230 through which the NASmessages can be transported. The NAS messages may be transported usingthe AS of the Uu and NG interfaces. NAS protocols 217 and 237 mayprovide control plane functionality such as authentication, security,connection setup, mobility management, and session management.

The RRCs 216 and 226 may provide control plane functionality between theUE 210 and the gNB 220 or, more generally, between the UE 210 and theRAN. The RRCs 216 and 226 may provide control plane functionalitybetween the UE 210 and the gNB 220 via signaling messages, referred toas RRC messages. RRC messages may be transmitted between the UE 210 andthe RAN using signaling radio bearers and the same/similar PDCP, RLC,MAC, and PHY protocol layers. The MAC may multiplex control-plane anduser-plane data into the same transport block (TB). The RRCs 216 and 226may provide control plane functionality such as: broadcast of systeminformation related to AS and NAS; paging initiated by the CN or theRAN; establishment, maintenance and release of an RRC connection betweenthe UE 210 and the RAN; security functions including key management;establishment, configuration, maintenance and release of signaling radiobearers and data radio bearers; mobility functions; QoS managementfunctions; the UE measurement reporting and control of the reporting;detection of and recovery from radio link failure (RLF); and/or NASmessage transfer. As part of establishing an RRC connection, RRCs 216and 226 may establish an RRC context, which may involve configuringparameters for communication between the UE 210 and the RAN.

FIG. 6 is an example diagram showing RRC state transitions of a UE. TheUE may be the same or similar to the wireless device 106 depicted inFIG. 1A, the UE 210 depicted in FIG. 2A and FIG. 2B, or any otherwireless device described in the present disclosure. As illustrated inFIG. 6 , a UE may be in at least one of three RRC states: RRC connected602 (e.g., RRC_CONNECTED), RRC idle 604 (e.g., RRC_IDLE), and RRCinactive 606 (e.g., RRC_INACTIVE).

In RRC connected 602, the UE has an established RRC context and may haveat least one RRC connection with a base station. The base station may besimilar to one of the one or more base stations included in the RAN 104depicted in FIG. 1A, one of the gNBs 160 or ng-eNBs 162 depicted in FIG.1B, the gNB 220 depicted in FIG. 2A and FIG. 2B, or any other basestation described in the present disclosure. The base station with whichthe UE is connected may have the RRC context for the UE. The RRCcontext, referred to as the UE context, may comprise parameters forcommunication between the UE and the base station. These parameters mayinclude, for example: one or more AS contexts; one or more radio linkconfiguration parameters; bearer configuration information (e.g.,relating to a data radio bearer, signaling radio bearer, logicalchannel, QoS flow, and/or PDU session); security information; and/orPHY, MAC, RLC, PDCP, and/or SDAP layer configuration information. Whilein RRC connected 602, mobility of the UE may be managed by the RAN(e.g., the RAN 104 or the NG-RAN 154). The UE may measure the signallevels (e.g., reference signal levels) from a serving cell andneighboring cells and report these measurements to the base stationcurrently serving the UE. The UE's serving base station may request ahandover to a cell of one of the neighboring base stations based on thereported measurements. The RRC state may transition from RRC connected602 to RRC idle 604 through a connection release procedure 608 or to RRCinactive 606 through a connection inactivation procedure 610.

In RRC idle 604, an RRC context may not be established for the UE. InRRC idle 604, the UE may not have an RRC connection with the basestation. While in RRC idle 604, the UE may be in a sleep state for themajority of the time (e.g., to conserve battery power). The UE may wakeup periodically (e.g., once in every discontinuous reception cycle) tomonitor for paging messages from the RAN. Mobility of the UE may bemanaged by the UE through a procedure known as cell reselection. The RRCstate may transition from RRC idle 604 to RRC connected 602 through aconnection establishment procedure 612, which may involve a randomaccess procedure as discussed in greater detail below.

In RRC inactive 606, the RRC context previously established ismaintained in the UE and the base station. This allows for a fasttransition to RRC connected 602 with reduced signaling overhead ascompared to the transition from RRC idle 604 to RRC connected 602. Whilein RRC inactive 606, the UE may be in a sleep state and mobility of theUE may be managed by the UE through cell reselection. The RRC state maytransition from RRC inactive 606 to RRC connected 602 through aconnection resume procedure 614 or to RRC idle 604 though a connectionrelease procedure 616 that may be the same as or similar to connectionrelease procedure 608.

An RRC state may be associated with a mobility management mechanism. InRRC idle 604 and RRC inactive 606, mobility is managed by the UE throughcell reselection. The purpose of mobility management in RRC idle 604 andRRC inactive 606 is to allow the network to be able to notify the UE ofan event via a paging message without having to broadcast the pagingmessage over the entire mobile communications network. The mobilitymanagement mechanism used in RRC idle 604 and RRC inactive 606 may allowthe network to track the UE on a cell-group level so that the pagingmessage may be broadcast over the cells of the cell group that the UEcurrently resides within instead of the entire mobile communicationnetwork. The mobility management mechanisms for RRC idle 604 and RRCinactive 606 track the UE on a cell-group level. They may do so usingdifferent granularities of grouping. For example, there may be threelevels of cell-grouping granularity: individual cells; cells within aRAN area identified by a RAN area identifier (RAI); and cells within agroup of RAN areas, referred to as a tracking area and identified by atracking area identifier (TAI).

Tracking areas may be used to track the UE at the CN level. The CN(e.g., the CN 102 or the 5G-CN 152) may provide the UE with a list ofTAIs associated with a UE registration area. If the UE moves, throughcell reselection, to a cell associated with a TAI not included in thelist of TAIs associated with the UE registration area, the UE mayperform a registration update with the CN to allow the CN to update theUE's location and provide the UE with a new the UE registration area.

RAN areas may be used to track the UE at the RAN level. For a UE in RRCinactive 606 state, the UE may be assigned a RAN notification area. ARAN notification area may comprise one or more cell identities, a listof RAIs, or a list of TAIs. In an example, a base station may belong toone or more RAN notification areas. In an example, a cell may belong toone or more RAN notification areas. If the UE moves, through cellreselection, to a cell not included in the RAN notification areaassigned to the UE, the UE may perform a notification area update withthe RAN to update the UE's RAN notification area.

A base station storing an RRC context for a UE or a last serving basestation of the UE may be referred to as an anchor base station. Ananchor base station may maintain an RRC context for the UE at leastduring a period of time that the UE stays in a RAN notification area ofthe anchor base station and/or during a period of time that the UE staysin RRC inactive 606.

A gNB, such as gNBs 160 in FIG. 1B, may be split in two parts: a centralunit (gNB-CU), and one or more distributed units (gNB-DU). A gNB-CU maybe coupled to one or more gNB-DUs using an F1 interface. The gNB-CU maycomprise the RRC, the PDCP, and the SDAP. A gNB-DU may comprise the RLC,the MAC, and the PHY.

In NR, the physical signals and physical channels (discussed withrespect to FIG. 5A and FIG. 5B) may be mapped onto orthogonal frequencydivisional multiplexing (OFDM) symbols. OFDM is a multicarriercommunication scheme that transmits data over F orthogonal subcarriers(or tones). Before transmission, the data may be mapped to a series ofcomplex symbols (e.g., M-quadrature amplitude modulation (M-QAM) orM-phase shift keying (M-PSK) symbols), referred to as source symbols,and divided into F parallel symbol streams. The F parallel symbolstreams may be treated as though they are in the frequency domain andused as inputs to an Inverse Fast Fourier Transform (IFFT) block thattransforms them into the time domain. The IFFT block may take in Fsource symbols at a time, one from each of the F parallel symbolstreams, and use each source symbol to modulate the amplitude and phaseof one of F sinusoidal basis functions that correspond to the Forthogonal subcarriers. The output of the IFFT block may be Ftime-domain samples that represent the summation of the F orthogonalsubcarriers. The F time-domain samples may form a single OFDM symbol.After some processing (e.g., addition of a cyclic prefix) andup-conversion, an OFDM symbol provided by the IFFT block may betransmitted over the air interface on a carrier frequency. The Fparallel symbol streams may be mixed using an FFT block before beingprocessed by the IFFT block. This operation produces Discrete FourierTransform (DFT)-precoded OFDM symbols and may be used by UEs in theuplink to reduce the peak to average power ratio (PAPR). Inverseprocessing may be performed on the OFDM symbol at a receiver using anFFT block to recover the data mapped to the source symbols.

FIG. 7 illustrates an example configuration of an NR frame into whichOFDM symbols are grouped. An NR frame may be identified by a systemframe number (SFN). The SFN may repeat with a period of 1024 frames. Asillustrated, one NR frame may be 10 milliseconds (ms) in duration andmay include 10 subframes that are 1 ms in duration. A subframe may bedivided into slots that include, for example, 14 OFDM symbols per slot.

The duration of a slot may depend on the numerology used for the OFDMsymbols of the slot. In NR, a flexible numerology is supported toaccommodate different cell deployments (e.g., cells with carrierfrequencies below 1 GHz up to cells with carrier frequencies in themm-wave range). A numerology may be defined in terms of subcarrierspacing and cyclic prefix duration. For a numerology in NR, subcarrierspacings may be scaled up by powers of two from a baseline subcarrierspacing of 15 kHz, and cyclic prefix durations may be scaled down bypowers of two from a baseline cyclic prefix duration of 4.7 μs. Forexample, NR defines numerologies with the following subcarrierspacing/cyclic prefix duration combinations: 15 kHz/4.7 μs; 30 kHz/2.3μs; 60 kHz/1.2 μs; 120 kHz/0.59 μs; and 240 kHz/0.29 μs.

A slot may have a fixed number of OFDM symbols (e.g., 14 OFDM symbols).A numerology with a higher subcarrier spacing has a shorter slotduration and, correspondingly, more slots per subframe. FIG. 7illustrates this numerology-dependent slot duration andslots-per-subframe transmission structure (the numerology with asubcarrier spacing of 240 kHz is not shown in FIG. 7 for ease ofillustration). A subframe in NR may be used as a numerology-independenttime reference, while a slot may be used as the unit upon which uplinkand downlink transmissions are scheduled. To support low latency,scheduling in NR may be decoupled from the slot duration and start atany OFDM symbol and last for as many symbols as needed for atransmission. These partial slot transmissions may be referred to asmini-slot or subslot transmissions.

FIG. 8 illustrates an example configuration of a slot in the time andfrequency domain for an NR carrier. The slot includes resource elements(REs) and resource blocks (RBs). An RE is the smallest physical resourcein NR. An RE spans one OFDM symbol in the time domain by one subcarrierin the frequency domain as shown in FIG. 8 . An RB spans twelveconsecutive REs in the frequency domain as shown in FIG. 8 . An NRcarrier may be limited to a width of 275 RBs or 275×12=3300 subcarriers.Such a limitation, if used, may limit the NR carrier to 50, 100, 200,and 400 MHz for subcarrier spacings of 15, 30, 60, and 120 kHz,respectively, where the 400 MHz bandwidth may be set based on a 400 MHzper carrier bandwidth limit.

FIG. 8 illustrates a single numerology being used across the entirebandwidth of the NR carrier. In other example configurations, multiplenumerologies may be supported on the same carrier.

NR may support wide carrier bandwidths (e.g., up to 400 MHz for asubcarrier spacing of 120 kHz). Not all UEs may be able to receive thefull carrier bandwidth (e.g., due to hardware limitations). Also,receiving the full carrier bandwidth may be prohibitive in terms of UEpower consumption. In an example, to reduce power consumption and/or forother purposes, a UE may adapt the size of the UE's receive bandwidthbased on the amount of traffic the UE is scheduled to receive. This isreferred to as bandwidth adaptation.

NR defines bandwidth parts (BWPs) to support UEs not capable ofreceiving the full carrier bandwidth and to support bandwidthadaptation. In an example, a BWP may be defined by a subset ofcontiguous RBs on a carrier. A UE may be configured (e.g., via RRClayer) with one or more downlink BWPs and one or more uplink BWPs perserving cell (e.g., up to four downlink BWPs and up to four uplink BWPsper serving cell). At a given time, one or more of the configured BWPsfor a serving cell may be active. These one or more BWPs may be referredto as active BWPs of the serving cell. When a serving cell is configuredwith a secondary uplink carrier, the serving cell may have one or morefirst active BWPs in the uplink carrier and one or more second activeBWPs in the secondary uplink carrier.

For unpaired spectra, a downlink BWP from a set of configured downlinkBWPs may be linked with an uplink BWP from a set of configured uplinkBWPs if a downlink BWP index of the downlink BWP and an uplink BWP indexof the uplink BWP are the same. For unpaired spectra, a UE may expectthat a center frequency for a downlink BWP is the same as a centerfrequency for an uplink BWP.

For a downlink BWP in a set of configured downlink BWPs on a primarycell (PCell), a base station may configure a UE with one or more controlresource sets (CORESETs) for at least one search space. A search spaceis a set of locations in the time and frequency domains where the UE mayfind control information. The search space may be a UE-specific searchspace or a common search space (potentially usable by a plurality ofUEs). For example, a base station may configure a UE with a commonsearch space, on a PCell or on a primary secondary cell (PSCell), in anactive downlink BWP.

For an uplink BWP in a set of configured uplink BWPs, a BS may configurea UE with one or more resource sets for one or more PUCCH transmissions.A UE may receive downlink receptions (e.g., PDCCH or PDSCH) in adownlink BWP according to a configured numerology (e.g., subcarrierspacing and cyclic prefix duration) for the downlink BWP. The UE maytransmit uplink transmissions (e.g., PUCCH or PUSCH) in an uplink BWPaccording to a configured numerology (e.g., subcarrier spacing andcyclic prefix length for the uplink BWP).

One or more BWP indicator fields may be provided in Downlink ControlInformation (DCI). A value of a BWP indicator field may indicate whichBWP in a set of configured BWPs is an active downlink BWP for one ormore downlink receptions. The value of the one or more BWP indicatorfields may indicate an active uplink BWP for one or more uplinktransmissions.

A base station may semi-statically configure a UE with a defaultdownlink BWP within a set of configured downlink BWPs associated with aPCell. If the base station does not provide the default downlink BWP tothe UE, the default downlink BWP may be an initial active downlink BWP.The UE may determine which BWP is the initial active downlink BWP basedon a CORESET configuration obtained using the PBCH.

A base station may configure a UE with a BWP inactivity timer value fora PCell. The UE may start or restart a BWP inactivity timer at anyappropriate time. For example, the UE may start or restart the BWPinactivity timer (a) when the UE detects a DCI indicating an activedownlink BWP other than a default downlink BWP for a paired spectraoperation; or (b) when a UE detects a DCI indicating an active downlinkBWP or active uplink BWP other than a default downlink BWP or uplink BWPfor an unpaired spectra operation. If the UE does not detect DCI duringan interval of time (e.g., 1 ms or 0.5 ms), the UE may run the BWPinactivity timer toward expiration (for example, increment from zero tothe BWP inactivity timer value, or decrement from the BWP inactivitytimer value to zero). When the BWP inactivity timer expires, the UE mayswitch from the active downlink BWP to the default downlink BWP.

In an example, a base station may semi-statically configure a UE withone or more BWPs. A UE may switch an active BWP from a first BWP to asecond BWP in response to receiving a DCI indicating the second BWP asan active BWP and/or in response to an expiry of the BWP inactivitytimer (e.g., if the second BWP is the default BWP).

Downlink and uplink BWP switching (where BWP switching refers toswitching from a currently active BWP to a not currently active BWP) maybe performed independently in paired spectra. In unpaired spectra,downlink and uplink BWP switching may be performed simultaneously.Switching between configured BWPs may occur based on RRC signaling, DCI,expiration of a BWP inactivity timer, and/or an initiation of randomaccess.

FIG. 9 illustrates an example of bandwidth adaptation using threeconfigured BWPs for an NR carrier. A UE configured with the three BWPsmay switch from one BWP to another BWP at a switching point. In theexample illustrated in FIG. 9 , the BWPs include: a BWP 902 with abandwidth of 40 MHz and a subcarrier spacing of 15 kHz; a BWP 904 with abandwidth of 10 MHz and a subcarrier spacing of 15 kHz; and a BWP 906with a bandwidth of 20 MHz and a subcarrier spacing of 60 kHz. The BWP902 may be an initial active BWP, and the BWP 904 may be a default BWP.The UE may switch between BWPs at switching points. In the example ofFIG. 9 , the UE may switch from the BWP 902 to the BWP 904 at aswitching point 908. The switching at the switching point 908 may occurfor any suitable reason, for example, in response to an expiry of a BWPinactivity timer (indicating switching to the default BWP) and/or inresponse to receiving a DCI indicating BWP 904 as the active BWP. The UEmay switch at a switching point 910 from active BWP 904 to BWP 906 inresponse receiving a DCI indicating BWP 906 as the active BWP. The UEmay switch at a switching point 912 from active BWP 906 to BWP 904 inresponse to an expiry of a BWP inactivity timer and/or in responsereceiving a DCI indicating BWP 904 as the active BWP. The UE may switchat a switching point 914 from active BWP 904 to BWP 902 in responsereceiving a DCI indicating BWP 902 as the active BWP.

If a UE is configured for a secondary cell with a default downlink BWPin a set of configured downlink BWPs and a timer value, UE proceduresfor switching BWPs on a secondary cell may be the same/similar as thoseon a primary cell. For example, the UE may use the timer value and thedefault downlink BWP for the secondary cell in the same/similar manneras the UE would use these values for a primary cell.

To provide for greater data rates, two or more carriers can beaggregated and simultaneously transmitted to/from the same UE usingcarrier aggregation (CA). The aggregated carriers in CA may be referredto as component carriers (CCs). When CA is used, there are a number ofserving cells for the UE, one for a CC. The CCs may have threeconfigurations in the frequency domain.

FIG. 10A illustrates the three CA configurations with two CCs. In theintraband, contiguous configuration 1002, the two CCs are aggregated inthe same frequency band (frequency band A) and are located directlyadjacent to each other within the frequency band. In the intraband,non-contiguous configuration 1004, the two CCs are aggregated in thesame frequency band (frequency band A) and are separated in thefrequency band by a gap. In the interband configuration 1006, the twoCCs are located in frequency bands (frequency band A and frequency bandB).

In an example, up to 32 CCs may be aggregated. The aggregated CCs mayhave the same or different bandwidths, subcarrier spacing, and/orduplexing schemes (TDD or FDD). A serving cell for a UE using CA mayhave a downlink CC. For FDD, one or more uplink CCs may be optionallyconfigured for a serving cell. The ability to aggregate more downlinkcarriers than uplink carriers may be useful, for example, when the UEhas more data traffic in the downlink than in the uplink.

When CA is used, one of the aggregated cells for a UE may be referred toas a primary cell (PCell). The PCell may be the serving cell that the UEinitially connects to at RRC connection establishment, reestablishment,and/or handover. The PCell may provide the UE with NAS mobilityinformation and the security input. UEs may have different PCells. Inthe downlink, the carrier corresponding to the PCell may be referred toas the downlink primary CC (DL PCC). In the uplink, the carriercorresponding to the PCell may be referred to as the uplink primary CC(UL PCC). The other aggregated cells for the UE may be referred to assecondary cells (SCells). In an example, the SCells may be configuredafter the PCell is configured for the UE. For example, an SCell may beconfigured through an RRC Connection Reconfiguration procedure. In thedownlink, the carrier corresponding to an SCell may be referred to as adownlink secondary CC (DL SCC). In the uplink, the carrier correspondingto the SCell may be referred to as the uplink secondary CC (UL SCC).

Configured SCells for a UE may be activated and deactivated based on,for example, traffic and channel conditions. Deactivation of an SCellmay mean that PDCCH and PDSCH reception on the SCell is stopped andPUSCH, SRS, and CQI transmissions on the SCell are stopped. ConfiguredSCells may be activated and deactivated using a MAC CE with respect toFIG. 4B. For example, a MAC CE may use a bitmap (e.g., one bit perSCell) to indicate which SCells (e.g., in a subset of configured SCells)for the UE are activated or deactivated. Configured SCells may bedeactivated in response to an expiration of an SCell deactivation timer(e.g., one SCell deactivation timer per SCell).

Downlink control information, such as scheduling assignments andscheduling grants, for a cell may be transmitted on the cellcorresponding to the assignments and grants, which is known asself-scheduling. The DCI for the cell may be transmitted on anothercell, which is known as cross-carrier scheduling. Uplink controlinformation (e.g., HARQ acknowledgments and channel state feedback, suchas CQI, PMI, and/or RI) for aggregated cells may be transmitted on thePUCCH of the PCell. For a larger number of aggregated downlink CCs, thePUCCH of the PCell may become overloaded. Cells may be divided intomultiple PUCCH groups.

FIG. 10B illustrates an example of how aggregated cells may beconfigured into one or more PUCCH groups. A PUCCH group 1010 and a PUCCHgroup 1050 may include one or more downlink CCs, respectively. In theexample of FIG. 10B, the PUCCH group 1010 includes three downlink CCs: aPCell 1011, an SCell 1012, and an SCell 1013. The PUCCH group 1050includes three downlink CCs in the present example: a PCell 1051, anSCell 1052, and an SCell 1053. One or more uplink CCs may be configuredas a PCell 1021, an SCell 1022, and an SCell 1023. One or more otheruplink CCs may be configured as a primary Scell (PSCell) 1061, an SCell1062, and an SCell 1063. Uplink control information (UCI) related to thedownlink CCs of the PUCCH group 1010, shown as UCI 1031, UCI 1032, andUCI 1033, may be transmitted in the uplink of the PCell 1021. Uplinkcontrol information (UCI) related to the downlink CCs of the PUCCH group1050, shown as UCI 1071, UCI 1072, and UCI 1073, may be transmitted inthe uplink of the PSCell 1061. In an example, if the aggregated cellsdepicted in FIG. 10B were not divided into the PUCCH group 1010 and thePUCCH group 1050, a single uplink PCell to transmit UCI relating to thedownlink CCs, and the PCell may become overloaded. By dividingtransmissions of UCI between the PCell 1021 and the PSCell 1061,overloading may be prevented.

A cell, comprising a downlink carrier and optionally an uplink carrier,may be assigned with a physical cell ID and a cell index. The physicalcell ID or the cell index may identify a downlink carrier and/or anuplink carrier of the cell, for example, depending on the context inwhich the physical cell ID is used. A physical cell ID may be determinedusing a synchronization signal transmitted on a downlink componentcarrier. A cell index may be determined using RRC messages. In thedisclosure, a physical cell ID may be referred to as a carrier ID, and acell index may be referred to as a carrier index. For example, when thedisclosure refers to a first physical cell ID for a first downlinkcarrier, the disclosure may mean the first physical cell ID is for acell comprising the first downlink carrier. The same/similar concept mayapply to, for example, a carrier activation. When the disclosureindicates that a first carrier is activated, the specification may meanthat a cell comprising the first carrier is activated.

In CA, a multi-carrier nature of a PHY may be exposed to a MAC. In anexample, a HARQ entity may operate on a serving cell. A transport blockmay be generated per assignment/grant per serving cell. A transportblock and potential HARQ retransmissions of the transport block may bemapped to a serving cell.

In the downlink, a base station may transmit (e.g., unicast, multicast,and/or broadcast) one or more Reference Signals (RSs) to a UE (e.g.,PSS, SSS, CSI-RS, DMRS, and/or PT-RS, as shown in FIG. 5A). In theuplink, the UE may transmit one or more RSs to the base station (e.g.,DMRS, PT-RS, and/or SRS, as shown in FIG. 5B). The PSS and the SSS maybe transmitted by the base station and used by the UE to synchronize theUE to the base station. The PSS and the SSS may be provided in asynchronization signal (SS)/physical broadcast channel (PBCH) block thatincludes the PSS, the SSS, and the PBCH. The base station mayperiodically transmit a burst of SS/PBCH blocks.

FIG. 11A illustrates an example of an SS/PBCH block's structure andlocation. A burst of SS/PBCH blocks may include one or more SS/PBCHblocks (e.g., 4 SS/PBCH blocks, as shown in FIG. 11A). Bursts may betransmitted periodically (e.g., every 2 frames or 20 ms). A burst may berestricted to a half-frame (e.g., a first half-frame having a durationof 5 ms). It will be understood that FIG. 11A is an example, and thatthese parameters (number of SS/PBCH blocks per burst, periodicity ofbursts, position of burst within the frame) may be configured based on,for example: a carrier frequency of a cell in which the SS/PBCH block istransmitted; a numerology or subcarrier spacing of the cell; aconfiguration by the network (e.g., using RRC signaling); or any othersuitable factor. In an example, the UE may assume a subcarrier spacingfor the SS/PBCH block based on the carrier frequency being monitored,unless the radio network configured the UE to assume a differentsubcarrier spacing.

The SS/PBCH block may span one or more OFDM symbols in the time domain(e.g., 4 OFDM symbols, as shown in the example of FIG. 11A) and may spanone or more subcarriers in the frequency domain (e.g., 240 contiguoussubcarriers). The PSS, the SSS, and the PBCH may have a common centerfrequency. The PSS may be transmitted first and may span, for example, 1OFDM symbol and 127 subcarriers. The SSS may be transmitted after thePSS (e.g., two symbols later) and may span 1 OFDM symbol and 127subcarriers. The PBCH may be transmitted after the PSS (e.g., across thenext 3 OFDM symbols) and may span 240 subcarriers.

The location of the SS/PBCH block in the time and frequency domains maynot be known to the UE (e.g., if the UE is searching for the cell). Tofind and select the cell, the UE may monitor a carrier for the PSS. Forexample, the UE may monitor a frequency location within the carrier. Ifthe PSS is not found after a certain duration (e.g., 20 ms), the UE maysearch for the PSS at a different frequency location within the carrier,as indicated by a synchronization raster. If the PSS is found at alocation in the time and frequency domains, the UE may determine, basedon a known structure of the SS/PBCH block, the locations of the SSS andthe PBCH, respectively. The SS/PBCH block may be a cell-defining SSblock (CD-SSB). In an example, a primary cell may be associated with aCD-SSB. The CD-SSB may be located on a synchronization raster. In anexample, a cell selection/search and/or reselection may be based on theCD-SSB.

The SS/PBCH block may be used by the UE to determine one or moreparameters of the cell. For example, the UE may determine a physicalcell identifier (PCI) of the cell based on the sequences of the PSS andthe SSS, respectively. The UE may determine a location of a frameboundary of the cell based on the location of the SS/PBCH block. Forexample, the SS/PBCH block may indicate that it has been transmitted inaccordance with a transmission pattern, wherein a SS/PBCH block in thetransmission pattern is a known distance from the frame boundary.

The PBCH may use a QPSK modulation and may use forward error correction(FEC). The FEC may use polar coding. One or more symbols spanned by thePBCH may carry one or more DMRSs for demodulation of the PBCH. The PBCHmay include an indication of a current system frame number (SFN) of thecell and/or a SS/PBCH block timing index. These parameters mayfacilitate time synchronization of the UE to the base station. The PBCHmay include a master information block (MIB) used to provide the UE withone or more parameters. The MIB may be used by the UE to locateremaining minimum system information (RMSI) associated with the cell.The RMSI may include a System Information Block Type 1 (SIB1). The SIB1may contain information needed by the UE to access the cell. The UE mayuse one or more parameters of the MIB to monitor PDCCH, which may beused to schedule PDSCH. The PDSCH may include the SIB1. The SIB1 may bedecoded using parameters provided in the MIB. The PBCH may indicate anabsence of SIB1. Based on the PBCH indicating the absence of SIB1, theUE may be pointed to a frequency. The UE may search for an SS/PBCH blockat the frequency to which the UE is pointed.

The UE may assume that one or more SS/PBCH blocks transmitted with asame SS/PBCH block index are quasi co-located (QCLed) (e.g., having thesame/similar Doppler spread, Doppler shift, average gain, average delay,and/or spatial Rx parameters). The UE may not assume QCL for SS/PBCHblock transmissions having different SS/PBCH block indices.

SS/PBCH blocks (e.g., those within a half-frame) may be transmitted inspatial directions (e.g., using different beams that span a coveragearea of the cell). In an example, a first SS/PBCH block may betransmitted in a first spatial direction using a first beam, and asecond SS/PBCH block may be transmitted in a second spatial directionusing a second beam.

In an example, within a frequency span of a carrier, a base station maytransmit a plurality of SS/PBCH blocks. In an example, a first PCI of afirst SS/PBCH block of the plurality of SS/PBCH blocks may be differentfrom a second PCI of a second SS/PBCH block of the plurality of SS/PBCHblocks. The PCIs of SS/PBCH blocks transmitted in different frequencylocations may be different or the same.

The CSI-RS may be transmitted by the base station and used by the UE toacquire channel state information (CSI). The base station may configurethe UE with one or more CSI-RSs for channel estimation or any othersuitable purpose. The base station may configure a UE with one or moreof the same/similar CSI-RSs. The UE may measure the one or more CSI-RSs.The UE may estimate a downlink channel state and/or generate a CSIreport based on the measuring of the one or more downlink CSI-RSs. TheUE may provide the CSI report to the base station. The base station mayuse feedback provided by the UE (e.g., the estimated downlink channelstate) to perform link adaptation.

The base station may semi-statically configure the UE with one or moreCSI-RS resource sets. A CSI-RS resource may be associated with alocation in the time and frequency domains and a periodicity. The basestation may selectively activate and/or deactivate a CSI-RS resource.The base station may indicate to the UE that a CSI-RS resource in theCSI-RS resource set is activated and/or deactivated.

The base station may configure the UE to report CSI measurements. Thebase station may configure the UE to provide CSI reports periodically,aperiodically, or semi-persistently. For periodic CSI reporting, the UEmay be configured with a timing and/or periodicity of a plurality of CSIreports. For aperiodic CSI reporting, the base station may request a CSIreport. For example, the base station may command the UE to measure aconfigured CSI-RS resource and provide a CSI report relating to themeasurements. For semi-persistent CSI reporting, the base station mayconfigure the UE to transmit periodically, and selectively activate ordeactivate the periodic reporting. The base station may configure the UEwith a CSI-RS resource set and CSI reports using RRC signaling.

The CSI-RS configuration may comprise one or more parameters indicating,for example, up to 32 antenna ports. The UE may be configured to employthe same OFDM symbols for a downlink CSI-RS and a control resource set(CORESET) when the downlink CSI-RS and CORESET are spatially QCLed andresource elements associated with the downlink CSI-RS are outside of thephysical resource blocks (PRBs) configured for the CORESET. The UE maybe configured to employ the same OFDM symbols for downlink CSI-RS andSS/PBCH blocks when the downlink CSI-RS and SS/PBCH blocks are spatiallyQCLed and resource elements associated with the downlink CSI-RS areoutside of PRBs configured for the SS/PBCH blocks.

Downlink DMRSs may be transmitted by a base station and used by a UE forchannel estimation. For example, the downlink DMRS may be used forcoherent demodulation of one or more downlink physical channels (e.g.,PDSCH). An NR network may support one or more variable and/orconfigurable DMRS patterns for data demodulation. At least one downlinkDMRS configuration may support a front-loaded DMRS pattern. Afront-loaded DMRS may be mapped over one or more OFDM symbols (e.g., oneor two adjacent OFDM symbols). A base station may semi-staticallyconfigure the UE with a number (e.g. a maximum number) of front-loadedDMRS symbols for PDSCH. A DMRS configuration may support one or moreDMRS ports. For example, for single user-MIMO, a DMRS configuration maysupport up to eight orthogonal downlink DMRS ports per UE. Formultiuser-MIMO, a DMRS configuration may support up to 4 orthogonaldownlink DMRS ports per UE. A radio network may support (e.g., at leastfor CP-OFDM) a common DMRS structure for downlink and uplink, wherein aDMRS location, a DMRS pattern, and/or a scrambling sequence may be thesame or different. The base station may transmit a downlink DMRS and acorresponding PDSCH using the same precoding matrix. The UE may use theone or more downlink DMRSs for coherent demodulation/channel estimationof the PDSCH.

In an example, a transmitter (e.g., a base station) may use a precodermatrices for a part of a transmission bandwidth. For example, thetransmitter may use a first precoder matrix for a first bandwidth and asecond precoder matrix for a second bandwidth. The first precoder matrixand the second precoder matrix may be different based on the firstbandwidth being different from the second bandwidth. The UE may assumethat a same precoding matrix is used across a set of PRBs. The set ofPRBs may be denoted as a precoding resource block group (PRG).

A PDSCH may comprise one or more layers. The UE may assume that at leastone symbol with DMRS is present on a layer of the one or more layers ofthe PDSCH. A higher layer may configure up to 3 DMRSs for the PDSCH.

Downlink PT-RS may be transmitted by a base station and used by a UE forphase-noise compensation. Whether a downlink PT-RS is present or not maydepend on an RRC configuration. The presence and/or pattern of thedownlink PT-RS may be configured on a UE-specific basis using acombination of RRC signaling and/or an association with one or moreparameters employed for other purposes (e.g., modulation and codingscheme (MCS)), which may be indicated by DCI. When configured, a dynamicpresence of a downlink PT-RS may be associated with one or more DCIparameters comprising at least MCS. An NR network may support aplurality of PT-RS densities defined in the time and/or frequencydomains. When present, a frequency domain density may be associated withat least one configuration of a scheduled bandwidth. The UE may assume asame precoding for a DMRS port and a PT-RS port. A number of PT-RS portsmay be fewer than a number of DMRS ports in a scheduled resource.Downlink PT-RS may be confined in the scheduled time/frequency durationfor the UE. Downlink PT-RS may be transmitted on symbols to facilitatephase tracking at the receiver.

The UE may transmit an uplink DMRS to a base station for channelestimation. For example, the base station may use the uplink DMRS forcoherent demodulation of one or more uplink physical channels. Forexample, the UE may transmit an uplink DMRS with a PUSCH and/or a PUCCH.The uplink DM-RS may span a range of frequencies that is similar to arange of frequencies associated with the corresponding physical channel.The base station may configure the UE with one or more uplink DMRSconfigurations. At least one DMRS configuration may support afront-loaded DMRS pattern. The front-loaded DMRS may be mapped over oneor more OFDM symbols (e.g., one or two adjacent OFDM symbols). One ormore uplink DMRSs may be configured to transmit at one or more symbolsof a PUSCH and/or a PUCCH. The base station may semi-staticallyconfigure the UE with a number (e.g. maximum number) of front-loadedDMRS symbols for the PUSCH and/or the PUCCH, which the UE may use toschedule a single-symbol DMRS and/or a double-symbol DMRS. An NR networkmay support (e.g., for cyclic prefix orthogonal frequency divisionmultiplexing (CP-OFDM)) a common DMRS structure for downlink and uplink,wherein a DMRS location, a DMRS pattern, and/or a scrambling sequencefor the DMRS may be the same or different.

A PUSCH may comprise one or more layers, and the UE may transmit atleast one symbol with DMRS present on a layer of the one or more layersof the PUSCH. In an example, a higher layer may configure up to threeDMRSs for the PUSCH.

Uplink PT-RS (which may be used by a base station for phase trackingand/or phase-noise compensation) may or may not be present depending onan RRC configuration of the UE. The presence and/or pattern of uplinkPT-RS may be configured on a UE-specific basis by a combination of RRCsignaling and/or one or more parameters employed for other purposes(e.g., Modulation and Coding Scheme (MCS)), which may be indicated byDCI. When configured, a dynamic presence of uplink PT-RS may beassociated with one or more DCI parameters comprising at least MCS. Aradio network may support a plurality of uplink PT-RS densities definedin time/frequency domain. When present, a frequency domain density maybe associated with at least one configuration of a scheduled bandwidth.The UE may assume a same precoding for a DMRS port and a PT-RS port. Anumber of PT-RS ports may be fewer than a number of DMRS ports in ascheduled resource. For example, uplink PT-RS may be confined in thescheduled time/frequency duration for the UE.

SRS may be transmitted by a UE to a base station for channel stateestimation to support uplink channel dependent scheduling and/or linkadaptation. SRS transmitted by the UE may allow a base station toestimate an uplink channel state at one or more frequencies. A schedulerat the base station may employ the estimated uplink channel state toassign one or more resource blocks for an uplink PUSCH transmission fromthe UE. The base station may semi-statically configure the UE with oneor more SRS resource sets. For an SRS resource set, the base station mayconfigure the UE with one or more SRS resources. An SRS resource setapplicability may be configured by a higher layer (e.g., RRC) parameter.For example, when a higher layer parameter indicates beam management, anSRS resource in a SRS resource set of the one or more SRS resource sets(e.g., with the same/similar time domain behavior, periodic, aperiodic,and/or the like) may be transmitted at a time instant (e.g.,simultaneously). The UE may transmit one or more SRS resources in SRSresource sets. An NR network may support aperiodic, periodic and/orsemi-persistent SRS transmissions. The UE may transmit SRS resourcesbased on one or more trigger types, wherein the one or more triggertypes may comprise higher layer signaling (e.g., RRC) and/or one or moreDCI formats. In an example, at least one DCI format may be employed forthe UE to select at least one of one or more configured SRS resourcesets. An SRS trigger type 0 may refer to an SRS triggered based on ahigher layer signaling. An SRS trigger type 1 may refer to an SRStriggered based on one or more DCI formats. In an example, when PUSCHand SRS are transmitted in a same slot, the UE may be configured totransmit SRS after a transmission of a PUSCH and a corresponding uplinkDMRS.

The base station may semi-statically configure the UE with one or moreSRS configuration parameters indicating at least one of following: a SRSresource configuration identifier; a number of SRS ports; time domainbehavior of an SRS resource configuration (e.g., an indication ofperiodic, semi-persistent, or aperiodic SRS); slot, mini-slot, and/orsubframe level periodicity; offset for a periodic and/or an aperiodicSRS resource; a number of OFDM symbols in an SRS resource; a startingOFDM symbol of an SRS resource; an SRS bandwidth; a frequency hoppingbandwidth; a cyclic shift; and/or an SRS sequence ID.

An antenna port is defined such that the channel over which a symbol onthe antenna port is conveyed can be inferred from the channel over whichanother symbol on the same antenna port is conveyed. If a first symboland a second symbol are transmitted on the same antenna port, thereceiver may infer the channel (e.g., fading gain, multipath delay,and/or the like) for conveying the second symbol on the antenna port,from the channel for conveying the first symbol on the antenna port. Afirst antenna port and a second antenna port may be referred to as quasico-located (QCLed) if one or more large-scale properties of the channelover which a first symbol on the first antenna port is conveyed may beinferred from the channel over which a second symbol on a second antennaport is conveyed. The one or more large-scale properties may comprise atleast one of: a delay spread; a Doppler spread; a Doppler shift; anaverage gain; an average delay; and/or spatial Receiving (Rx)parameters.

Channels that use beamforming require beam management. Beam managementmay comprise beam measurement, beam selection, and beam indication. Abeam may be associated with one or more reference signals. For example,a beam may be identified by one or more beamformed reference signals.The UE may perform downlink beam measurement based on downlink referencesignals (e.g., a channel state information reference signal (CSI-RS))and generate a beam measurement report. The UE may perform the downlinkbeam measurement procedure after an RRC connection is set up with a basestation.

FIG. 11B illustrates an example of channel state information referencesignals (CSI-RSs) that are mapped in the time and frequency domains. Asquare shown in FIG. 11B may span a resource block (RB) within abandwidth of a cell. A base station may transmit one or more RRCmessages comprising CSI-RS resource configuration parameters indicatingone or more CSI-RSs. One or more of the following parameters may beconfigured by higher layer signaling (e.g., RRC and/or MAC signaling)for a CSI-RS resource configuration: a CSI-RS resource configurationidentity, a number of CSI-RS ports, a CSI-RS configuration (e.g., symboland resource element (RE) locations in a subframe), a CSI-RS subframeconfiguration (e.g., subframe location, offset, and periodicity in aradio frame), a CSI-RS power parameter, a CSI-RS sequence parameter, acode division multiplexing (CDM) type parameter, a frequency density, atransmission comb, quasi co-location (QCL) parameters (e.g.,QCL-scramblingidentity, crs-portscount, mbsfn-subframeconfiglist,csi-rs-configZPid, qcl-csi-rs-configNZPid), and/or other radio resourceparameters.

The three beams illustrated in FIG. 11B may be configured for a UE in aUE-specific configuration. Three beams are illustrated in FIG. 11B (beam#1, beam #2, and beam #3), more or fewer beams may be configured. Beam#1 may be allocated with CSI-RS 1101 that may be transmitted in one ormore subcarriers in an RB of a first symbol. Beam #2 may be allocatedwith CSI-RS 1102 that may be transmitted in one or more subcarriers inan RB of a second symbol. Beam #3 may be allocated with CSI-RS 1103 thatmay be transmitted in one or more subcarriers in an RB of a thirdsymbol. By using frequency division multiplexing (FDM), a base stationmay use other subcarriers in a same RB (for example, those that are notused to transmit CSI-RS 1101) to transmit another CSI-RS associated witha beam for another UE. By using time domain multiplexing (TDM), beamsused for the UE may be configured such that beams for the UE use symbolsfrom beams of other UEs.

CSI-RSs such as those illustrated in FIG. 11B (e.g., CSI-RS 1101, 1102,1103) may be transmitted by the base station and used by the UE for oneor more measurements. For example, the UE may measure a reference signalreceived power (RSRP) of configured CSI-RS resources. The base stationmay configure the UE with a reporting configuration and the UE mayreport the RSRP measurements to a network (for example, via one or morebase stations) based on the reporting configuration. In an example, thebase station may determine, based on the reported measurement results,one or more transmission configuration indication (TCI) statescomprising a number of reference signals. In an example, the basestation may indicate one or more TCI states to the UE (e.g., via RRCsignaling, a MAC CE, and/or a DCI). The UE may receive a downlinktransmission with a receive (Rx) beam determined based on the one ormore TCI states. In an example, the UE may or may not have a capabilityof beam correspondence. If the UE has the capability of beamcorrespondence, the UE may determine a spatial domain filter of atransmit (Tx) beam based on a spatial domain filter of the correspondingRx beam. If the UE does not have the capability of beam correspondence,the UE may perform an uplink beam selection procedure to determine thespatial domain filter of the Tx beam. The UE may perform the uplink beamselection procedure based on one or more sounding reference signal (SRS)resources configured to the UE by the base station. The base station mayselect and indicate uplink beams for the UE based on measurements of theone or more SRS resources transmitted by the UE.

In a beam management procedure, a UE may assess (e.g., measure) achannel quality of one or more beam pair links, a beam pair linkcomprising a transmitting beam transmitted by a base station and areceiving beam received by the UE. Based on the assessment, the UE maytransmit a beam measurement report indicating one or more beam pairquality parameters comprising, e.g., one or more beam identifications(e.g., a beam index, a reference signal index, or the like), RSRP, aprecoding matrix indicator (PMI), a channel quality indicator (CQI),and/or a rank indicator (RI).

FIG. 12A illustrates examples of three downlink beam managementprocedures: P1, P2, and P3. Procedure P1 may enable a UE measurement ontransmit (Tx) beams of a transmission reception point (TRP) (or multipleTRPs), e.g., to support a selection of one or more base station Tx beamsand/or UE Rx beams (shown as ovals in the top row and bottom row,respectively, of P1). Beamforming at a TRP may comprise a Tx beam sweepfor a set of beams (shown, in the top rows of P1 and P2, as ovalsrotated in a counter-clockwise direction indicated by the dashed arrow).Beamforming at a UE may comprise an Rx beam sweep for a set of beams(shown, in the bottom rows of P1 and P3, as ovals rotated in a clockwisedirection indicated by the dashed arrow). Procedure P2 may be used toenable a UE measurement on Tx beams of a TRP (shown, in the top row ofP2, as ovals rotated in a counter-clockwise direction indicated by thedashed arrow). The UE and/or the base station may perform procedure P2using a smaller set of beams than is used in procedure P1, or usingnarrower beams than the beams used in procedure P1. This may be referredto as beam refinement. The UE may perform procedure P3 for Rx beamdetermination by using the same Tx beam at the base station and sweepingan Rx beam at the UE.

FIG. 12B illustrates examples of three uplink beam managementprocedures: U1, U2, and U3. Procedure U1 may be used to enable a basestation to perform a measurement on Tx beams of a UE, e.g., to support aselection of one or more UE Tx beams and/or base station Rx beams (shownas ovals in the top row and bottom row, respectively, of U1).Beamforming at the UE may include, e.g., a Tx beam sweep from a set ofbeams (shown in the bottom rows of U1 and U3 as ovals rotated in aclockwise direction indicated by the dashed arrow). Beamforming at thebase station may include, e.g., an Rx beam sweep from a set of beams(shown, in the top rows of U1 and U2, as ovals rotated in acounter-clockwise direction indicated by the dashed arrow). Procedure U2may be used to enable the base station to adjust its Rx beam when the UEuses a fixed Tx beam. The UE and/or the base station may performprocedure U2 using a smaller set of beams than is used in procedure P1,or using narrower beams than the beams used in procedure P1. This may bereferred to as beam refinement The UE may perform procedure U3 to adjustits Tx beam when the base station uses a fixed Rx beam.

A UE may initiate a beam failure recovery (BFR) procedure based ondetecting a beam failure. The UE may transmit a BFR request (e.g., apreamble, a UCI, an SR, a MAC CE, and/or the like) based on theinitiating of the BFR procedure. The UE may detect the beam failurebased on a determination that a quality of beam pair link(s) of anassociated control channel is unsatisfactory (e.g., having an error ratehigher than an error rate threshold, a received signal power lower thana received signal power threshold, an expiration of a timer, and/or thelike).

The UE may measure a quality of a beam pair link using one or morereference signals (RSs) comprising one or more SS/PBCH blocks, one ormore CSI-RS resources, and/or one or more demodulation reference signals(DMRSs). A quality of the beam pair link may be based on one or more ofa block error rate (BLER), an RSRP value, a signal to interference plusnoise ratio (SINR) value, a reference signal received quality (RSRQ)value, and/or a CSI value measured on RS resources. The base station mayindicate that an RS resource is quasi co-located (QCLed) with one ormore DM-RSs of a channel (e.g., a control channel, a shared datachannel, and/or the like). The RS resource and the one or more DMRSs ofthe channel may be QCLed when the channel characteristics (e.g., Dopplershift, Doppler spread, average delay, delay spread, spatial Rxparameter, fading, and/or the like) from a transmission via the RSresource to the UE are similar or the same as the channelcharacteristics from a transmission via the channel to the UE.

A network (e.g., a gNB and/or an ng-eNB of a network) and/or the UE mayinitiate a random access procedure. A UE in an RRC_IDLE state and/or anRRC_INACTIVE state may initiate the random access procedure to request aconnection setup to a network. The UE may initiate the random accessprocedure from an RRC_CONNECTED state. The UE may initiate the randomaccess procedure to request uplink resources (e.g., for uplinktransmission of an SR when there is no PUCCH resource available) and/oracquire uplink timing (e.g., when uplink synchronization status isnon-synchronized). The UE may initiate the random access procedure torequest one or more system information blocks (SIBs) (e.g., other systeminformation such as SIB2, SIB3, and/or the like). The UE may initiatethe random access procedure for a beam failure recovery request. Anetwork may initiate a random access procedure for a handover and/or forestablishing time alignment for an SCell addition.

FIG. 13A illustrates a four-step contention-based random accessprocedure. Prior to initiation of the procedure, a base station maytransmit a configuration message 1310 to the UE. The procedureillustrated in FIG. 13A comprises transmission of four messages: a Msg 11311, a Msg 2 1312, a Msg 3 1313, and a Msg 4 1314. The Msg 1 1311 mayinclude and/or be referred to as a preamble (or a random accesspreamble). The Msg 2 1312 may include and/or be referred to as a randomaccess response (RAR).

The configuration message 1310 may be transmitted, for example, usingone or more RRC messages. The one or more RRC messages may indicate oneor more random access channel (RACH) parameters to the UE. The one ormore RACH parameters may comprise at least one of following: generalparameters for one or more random access procedures (e.g.,RACH-configGeneral); cell-specific parameters (e.g., RACH-ConfigCommon);and/or dedicated parameters (e.g., RACH-configDedicated). The basestation may broadcast or multicast the one or more RRC messages to oneor more UEs. The one or more RRC messages may be UE-specific (e.g.,dedicated RRC messages transmitted to a UE in an RRC_CONNECTED stateand/or in an RRC_INACTIVE state). The UE may determine, based on the oneor more RACH parameters, a time-frequency resource and/or an uplinktransmit power for transmission of the Msg 1 1311 and/or the Msg 3 1313.Based on the one or more RACH parameters, the UE may determine areception timing and a downlink channel for receiving the Msg 2 1312 andthe Msg 4 1314.

The one or more RACH parameters provided in the configuration message1310 may indicate one or more Physical RACH (PRACH) occasions availablefor transmission of the Msg 1 1311. The one or more PRACH occasions maybe predefined. The one or more RACH parameters may indicate one or moreavailable sets of one or more PRACH occasions (e.g., prach-ConfigIndex).The one or more RACH parameters may indicate an association between (a)one or more PRACH occasions and (b) one or more reference signals. Theone or more RACH parameters may indicate an association between (a) oneor more preambles and (b) one or more reference signals. The one or morereference signals may be SS/PBCH blocks and/or CSI-RSs. For example, theone or more RACH parameters may indicate a number of SS/PBCH blocksmapped to a PRACH occasion and/or a number of preambles mapped to aSS/PBCH blocks.

The one or more RACH parameters provided in the configuration message1310 may be used to determine an uplink transmit power of Msg 1 1311and/or Msg 3 1313. For example, the one or more RACH parameters mayindicate a reference power for a preamble transmission (e.g., a receivedtarget power and/or an initial power of the preamble transmission).There may be one or more power offsets indicated by the one or more RACHparameters. For example, the one or more RACH parameters may indicate: apower ramping step; a power offset between SSB and CSI-RS; a poweroffset between transmissions of the Msg 1 1311 and the Msg 3 1313;and/or a power offset value between preamble groups. The one or moreRACH parameters may indicate one or more thresholds based on which theUE may determine at least one reference signal (e.g., an SSB and/orCSI-RS) and/or an uplink carrier (e.g., a normal uplink (NUL) carrierand/or a supplemental uplink (SUL) carrier).

The Msg 1 1311 may include one or more preamble transmissions (e.g., apreamble transmission and one or more preamble retransmissions). An RRCmessage may be used to configure one or more preamble groups (e.g.,group A and/or group B). A preamble group may comprise one or morepreambles. The UE may determine the preamble group based on a pathlossmeasurement and/or a size of the Msg 3 1313. The UE may measure an RSRPof one or more reference signals (e.g., SSBs and/or CSI-RSs) anddetermine at least one reference signal having an RSRP above an RSRPthreshold (e.g., rsrp-ThresholdSSB and/or rsrp-ThresholdCSI-RS). The UEmay select at least one preamble associated with the one or morereference signals and/or a selected preamble group, for example, if theassociation between the one or more preambles and the at least onereference signal is configured by an RRC message.

The UE may determine the preamble based on the one or more RACHparameters provided in the configuration message 1310. For example, theUE may determine the preamble based on a pathloss measurement, an RSRPmeasurement, and/or a size of the Msg 3 1313. As another example, theone or more RACH parameters may indicate: a preamble format; a maximumnumber of preamble transmissions; and/or one or more thresholds fordetermining one or more preamble groups (e.g., group A and group B). Abase station may use the one or more RACH parameters to configure the UEwith an association between one or more preambles and one or morereference signals (e.g., SSBs and/or CSI-RSs). If the association isconfigured, the UE may determine the preamble to include in Msg 1 1311based on the association. The Msg 1 1311 may be transmitted to the basestation via one or more PRACH occasions. The UE may use one or morereference signals (e.g., SSBs and/or CSI-RSs) for selection of thepreamble and for determining of the PRACH occasion. One or more RACHparameters (e.g., ra-ssb-OccasionMskIndex and/or ra-OccasionList) mayindicate an association between the PRACH occasions and the one or morereference signals.

The UE may perform a preamble retransmission if no response is receivedfollowing a preamble transmission. The UE may increase an uplinktransmit power for the preamble retransmission. The UE may select aninitial preamble transmit power based on a pathloss measurement and/or atarget received preamble power configured by the network. The UE maydetermine to retransmit a preamble and may ramp up the uplink transmitpower. The UE may receive one or more RACH parameters (e.g.,PREAMBLE_POWER_RAMPING_STEP) indicating a ramping step for the preambleretransmission. The ramping step may be an amount of incrementalincrease in uplink transmit power for a retransmission. The UE may rampup the uplink transmit power if the UE determines a reference signal(e.g., SSB and/or CSI-RS) that is the same as a previous preambletransmission. The UE may count a number of preamble transmissions and/orretransmissions (e.g., PREAMBLE_TRANSMISSION_COUNTER). The UE maydetermine that a random access procedure completed unsuccessfully, forexample, if the number of preamble transmissions exceeds a thresholdconfigured by the one or more RACH parameters (e.g., preambleTransMax).

The Msg 2 1312 received by the UE may include an RAR. In some scenarios,the Msg 2 1312 may include multiple RARs corresponding to multiple UEs.The Msg 2 1312 may be received after or in response to the transmittingof the Msg 1 1311. The Msg 2 1312 may be scheduled on the DL-SCH andindicated on a PDCCH using a random access RNTI (RA-RNTI). The Msg 21312 may indicate that the Msg 1 1311 was received by the base station.The Msg 2 1312 may include a time-alignment command that may be used bythe UE to adjust the UE's transmission timing, a scheduling grant fortransmission of the Msg 3 1313, and/or a Temporary Cell RNTI (TC-RNTI).After transmitting a preamble, the UE may start a time window (e.g.,ra-ResponseWindow) to monitor a PDCCH for the Msg 2 1312. The UE maydetermine when to start the time window based on a PRACH occasion thatthe UE uses to transmit the preamble. For example, the UE may start thetime window one or more symbols after a last symbol of the preamble(e.g., at a first PDCCH occasion from an end of a preambletransmission). The one or more symbols may be determined based on anumerology. The PDCCH may be in a common search space (e.g., aType1-PDCCH common search space) configured by an RRC message. The UEmay identify the RAR based on a Radio Network Temporary Identifier(RNTI). RNTIs may be used depending on one or more events initiating therandom access procedure. The UE may use random access RNTI (RA-RNTI).The RA-RNTI may be associated with PRACH occasions in which the UEtransmits a preamble. For example, the UE may determine the RA-RNTIbased on: an OFDM symbol index; a slot index; a frequency domain index;and/or a UL carrier indicator of the PRACH occasions. An example ofRA-RNTI may be as follows:

RA-RNTI=1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_id where s_id maybe an index of a first OFDM symbol of the PRACH occasion (e.g.,0≤s_id<14), t_id may be an index of a first slot of the PRACH occasionin a system frame (e.g., 0≤t_id<80), f_id may be an index of the PRACHoccasion in the frequency domain (e.g., 0≤f_id<8), and ul_carrier_id maybe a UL carrier used for a preamble transmission (e.g., 0 for an NULcarrier, and 1 for an SUL carrier).

The UE may transmit the Msg 3 1313 in response to a successful receptionof the Msg 2 1312 (e.g., using resources identified in the Msg 2 1312).The Msg 3 1313 may be used for contention resolution in, for example,the contention-based random access procedure illustrated in FIG. 13A. Insome scenarios, a plurality of UEs may transmit a same preamble to abase station and the base station may provide an RAR that corresponds toa UE. Collisions may occur if the plurality of UEs interpret the RAR ascorresponding to themselves. Contention resolution (e.g., using the Msg3 1313 and the Msg 4 1314) may be used to increase the likelihood thatthe UE does not incorrectly use an identity of another the UE. Toperform contention resolution, the UE may include a device identifier inthe Msg 3 1313 (e.g., a C-RNTI if assigned, a TC-RNTI included in theMsg 2 1312, and/or any other suitable identifier).

The Msg 4 1314 may be received after or in response to the transmittingof the Msg 3 1313. If a C-RNTI was included in the Msg 3 1313, the basestation will address the UE on the PDCCH using the C-RNTI. If the UE'sunique C-RNTI is detected on the PDCCH, the random access procedure isdetermined to be successfully completed. If a TC-RNTI is included in theMsg 3 1313 (e.g., if the UE is in an RRC_IDLE state or not otherwiseconnected to the base station), Msg 4 1314 will be received using aDL-SCH associated with the TC-RNTI. If a MAC PDU is successfully decodedand a MAC PDU comprises the UE contention resolution identity MAC CEthat matches or otherwise corresponds with the CCCH SDU sent (e.g.,transmitted) in Msg 3 1313, the UE may determine that the contentionresolution is successful and/or the UE may determine that the randomaccess procedure is successfully completed.

The UE may be configured with a supplementary uplink (SUL) carrier and anormal uplink (NUL) carrier. An initial access (e.g., random accessprocedure) may be supported in an uplink carrier. For example, a basestation may configure the UE with two separate RACH configurations: onefor an SUL carrier and the other for an NUL carrier. For random accessin a cell configured with an SUL carrier, the network may indicate whichcarrier to use (NUL or SUL). The UE may determine the SUL carrier, forexample, if a measured quality of one or more reference signals is lowerthan a broadcast threshold. Uplink transmissions of the random accessprocedure (e.g., the Msg 1 1311 and/or the Msg 3 1313) may remain on theselected carrier. The UE may switch an uplink carrier during the randomaccess procedure (e.g., between the Msg 1 1311 and the Msg 3 1313) inone or more cases. For example, the UE may determine and/or switch anuplink carrier for the Msg 1 1311 and/or the Msg 3 1313 based on achannel clear assessment (e.g., a listen-before-talk).

FIG. 13B illustrates a two-step contention-free random access procedure.Similar to the four-step contention-based random access procedureillustrated in FIG. 13A, a base station may, prior to initiation of theprocedure, transmit a configuration message 1320 to the UE. Theconfiguration message 1320 may be analogous in some respects to theconfiguration message 1310. The procedure illustrated in FIG. 13Bcomprises transmission of two messages: a Msg 1 1321 and a Msg 2 1322.The Msg 1 1321 and the Msg 2 1322 may be analogous in some respects tothe Msg 1 1311 and a Msg 2 1312 illustrated in FIG. 13A, respectively.As will be understood from FIGS. 13A and 13B, the contention-free randomaccess procedure may not include messages analogous to the Msg 3 1313and/or the Msg 4 1314.

The contention-free random access procedure illustrated in FIG. 13B maybe initiated for a beam failure recovery, other SI request, SCelladdition, and/or handover. For example, a base station may indicate orassign to the UE the preamble to be used for the Msg 1 1321. The UE mayreceive, from the base station via PDCCH and/or RRC, an indication of apreamble (e.g., ra-PreambleIndex).

After transmitting a preamble, the UE may start a time window (e.g.,ra-ResponseWindow) to monitor a PDCCH for the RAR. In the event of abeam failure recovery request, the base station may configure the UEwith a separate time window and/or a separate PDCCH in a search spaceindicated by an RRC message (e.g., recoverySearchSpaceId). The UE maymonitor for a PDCCH transmission addressed to a Cell RNTI (C-RNTI) onthe search space. In the contention-free random access procedureillustrated in FIG. 13B, the UE may determine that a random accessprocedure successfully completes after or in response to transmission ofMsg 1 1321 and reception of a corresponding Msg 2 1322. The UE maydetermine that a random access procedure successfully completes, forexample, if a PDCCH transmission is addressed to a C-RNTI. The UE maydetermine that a random access procedure successfully completes, forexample, if the UE receives an RAR comprising a preamble identifiercorresponding to a preamble transmitted by the UE and/or the RARcomprises a MAC sub-PDU with the preamble identifier. The UE maydetermine the response as an indication of an acknowledgement for an SIrequest.

FIG. 13C illustrates another two-step random access procedure. Similarto the random access procedures illustrated in FIGS. 13A and 13B, a basestation may, prior to initiation of the procedure, transmit aconfiguration message 1330 to the UE. The configuration message 1330 maybe analogous in some respects to the configuration message 1310 and/orthe configuration message 1320. The procedure illustrated in FIG. 13Ccomprises transmission of two messages: a Msg A 1331 and a Msg B 1332.

Msg A 1331 may be transmitted in an uplink transmission by the UE. Msg A1331 may comprise one or more transmissions of a preamble 1341 and/orone or more transmissions of a transport block 1342. The transport block1342 may comprise contents that are similar and/or equivalent to thecontents of the Msg 3 1313 illustrated in FIG. 13A. The transport block1342 may comprise UCI (e.g., an SR, a HARQ ACK/NACK, and/or the like).The UE may receive the Msg B 1332 after or in response to transmittingthe Msg A 1331. The Msg B 1332 may comprise contents that are similarand/or equivalent to the contents of the Msg 2 1312 (e.g., an RAR)illustrated in FIGS. 13A and 13B and/or the Msg 4 1314 illustrated inFIG. 13A.

The UE may initiate the two-step random access procedure in FIG. 13C forlicensed spectrum and/or unlicensed spectrum. The UE may determine,based on one or more factors, whether to initiate the two-step randomaccess procedure. The one or more factors may be: a radio accesstechnology in use (e.g., LTE, NR, and/or the like); whether the UE hasvalid TA or not; a cell size; the UE's RRC state; a type of spectrum(e.g., licensed vs. unlicensed); and/or any other suitable factors.

The UE may determine, based on two-step RACH parameters included in theconfiguration message 1330, a radio resource and/or an uplink transmitpower for the preamble 1341 and/or the transport block 1342 included inthe Msg A 1331. The RACH parameters may indicate a modulation and codingschemes (MCS), a time-frequency resource, and/or a power control for thepreamble 1341 and/or the transport block 1342. A time-frequency resourcefor transmission of the preamble 1341 (e.g., a PRACH) and atime-frequency resource for transmission of the transport block 1342(e.g., a PUSCH) may be multiplexed using FDM, TDM, and/or CDM. The RACHparameters may enable the UE to determine a reception timing and adownlink channel for monitoring for and/or receiving Msg B 1332.

The transport block 1342 may comprise data (e.g., delay-sensitive data),an identifier of the UE, security information, and/or device information(e.g., an International Mobile Subscriber Identity (IMSI)). The basestation may transmit the Msg B 1332 as a response to the Msg A 1331. TheMsg B 1332 may comprise at least one of following: a preambleidentifier; a timing advance command; a power control command; an uplinkgrant (e.g., a radio resource assignment and/or an MCS); a UE identifierfor contention resolution; and/or an RNTI (e.g., a C-RNTI or a TC-RNTI).The UE may determine that the two-step random access procedure issuccessfully completed if: a preamble identifier in the Msg B 1332 ismatched to a preamble transmitted by the UE; and/or the identifier ofthe UE in Msg B 1332 is matched to the identifier of the UE in the Msg A1331 (e.g., the transport block 1342).

A UE and a base station may exchange control signaling. The controlsignaling may be referred to as L1/L2 control signaling and mayoriginate from the PHY layer (e.g., layer 1) and/or the MAC layer (e.g.,layer 2). The control signaling may comprise downlink control signalingtransmitted from the base station to the UE and/or uplink controlsignaling transmitted from the UE to the base station.

The downlink control signaling may comprise: a downlink schedulingassignment; an uplink scheduling grant indicating uplink radio resourcesand/or a transport format; a slot format information; a preemptionindication; a power control command; and/or any other suitablesignaling. The UE may receive the downlink control signaling in apayload transmitted by the base station on a physical downlink controlchannel (PDCCH). The payload transmitted on the PDCCH may be referred toas downlink control information (DCI). In some scenarios, the PDCCH maybe a group common PDCCH (GC-PDCCH) that is common to a group of UEs.

A base station may attach one or more cyclic redundancy check (CRC)parity bits to a DCI in order to facilitate detection of transmissionerrors. When the DCI is intended for a UE (or a group of the UEs), thebase station may scramble the CRC parity bits with an identifier of theUE (or an identifier of the group of the UEs). Scrambling the CRC paritybits with the identifier may comprise Modulo-2 addition (or an exclusiveOR operation) of the identifier value and the CRC parity bits. Theidentifier may comprise a 16-bit value of a radio network temporaryidentifier (RNTI).

DCIs may be used for different purposes. A purpose may be indicated bythe type of RNTI used to scramble the CRC parity bits. For example, aDCI having CRC parity bits scrambled with a paging RNTI (P-RNTI) mayindicate paging information and/or a system information changenotification. The P-RNTI may be predefined as “FFFE” in hexadecimal. ADCI having CRC parity bits scrambled with a system information RNTI(SI-RNTI) may indicate a broadcast transmission of the systeminformation. The SI-RNTI may be predefined as “FFFF” in hexadecimal. ADCI having CRC parity bits scrambled with a random access RNTI (RA-RNTI)may indicate a random access response (RAR). A DCI having CRC paritybits scrambled with a cell RNTI (C-RNTI) may indicate a dynamicallyscheduled unicast transmission and/or a triggering of PDCCH-orderedrandom access. A DCI having CRC parity bits scrambled with a temporarycell RNTI (TC-RNTI) may indicate a contention resolution (e.g., a Msg 3analogous to the Msg 3 1313 illustrated in FIG. 13A). Other RNTIsconfigured to the UE by a base station may comprise a ConfiguredScheduling RNTI (CS-RNTI), a Transmit Power Control-PUCCH RNTI(TPC-PUCCH-RNTI), a Transmit Power Control-PUSCH RNTI (TPC-PUSCH-RNTI),a Transmit Power Control-SRS RNTI (TPC-SRS-RNTI), an Interruption RNTI(INT-RNTI), a Slot Format Indication RNTI (SFI-RNTI), a Semi-PersistentCSI RNTI (SP-CSI-RNTI), a Modulation and Coding Scheme Cell RNTI(MCS-C-RNTI), and/or the like.

Depending on the purpose and/or content of a DCI, the base station maytransmit the DCIs with one or more DCI formats. For example, DCI format0_0 may be used for scheduling of PUSCH in a cell. DCI format 0_0 may bea fallback DCI format (e.g., with compact DCI payloads). DCI format 0_1may be used for scheduling of PUSCH in a cell (e.g., with more DCIpayloads than DCI format 0_0). DCI format 1_0 may be used for schedulingof PDSCH in a cell. DCI format 1_0 may be a fallback DCI format (e.g.,with compact DCI payloads). DCI format 1_1 may be used for scheduling ofPDSCH in a cell (e.g., with more DCI payloads than DCI format 1_0). DCIformat 2_0 may be used for providing a slot format indication to a groupof UEs. DCI format 2_1 may be used for notifying a group of UEs of aphysical resource block and/or OFDM symbol where the UE may assume notransmission is intended to the UE. DCI format 2_2 may be used fortransmission of a transmit power control (TPC) command for PUCCH orPUSCH. DCI format 2_3 may be used for transmission of a group of TPCcommands for SRS transmissions by one or more UEs. DCI format(s) for newfunctions may be defined in future releases. DCI formats may havedifferent DCI sizes, or may share the same DCI size.

After scrambling a DCI with a RNTI, the base station may process the DCIwith channel coding (e.g., polar coding), rate matching, scramblingand/or QPSK modulation. A base station may map the coded and modulatedDCI on resource elements used and/or configured for a PDCCH. Based on apayload size of the DCI and/or a coverage of the base station, the basestation may transmit the DCI via a PDCCH occupying a number ofcontiguous control channel elements (CCEs). The number of the contiguousCCEs (referred to as aggregation level) may be 1, 2, 4, 8, 16, and/orany other suitable number. A CCE may comprise a number (e.g., 6) ofresource-element groups (REGs). A REG may comprise a resource block inan OFDM symbol. The mapping of the coded and modulated DCI on theresource elements may be based on mapping of CCEs and REGs (e.g.,CCE-to-REG mapping).

FIG. 14A illustrates an example of CORESET configurations for abandwidth part. The base station may transmit a DCI via a PDCCH on oneor more control resource sets (CORESETs). A CORESET may comprise atime-frequency resource in which the UE tries to decode a DCI using oneor more search spaces. The base station may configure a CORESET in thetime-frequency domain. In the example of FIG. 14A, a first CORESET 1401and a second CORESET 1402 occur at the first symbol in a slot. The firstCORESET 1401 overlaps with the second CORESET 1402 in the frequencydomain. A third CORESET 1403 occurs at a third symbol in the slot. Afourth CORESET 1404 occurs at the seventh symbol in the slot. CORESETsmay have a different number of resource blocks in frequency domain.

FIG. 14B illustrates an example of a CCE-to-REG mapping for DCItransmission on a CORESET and PDCCH processing. The CCE-to-REG mappingmay be an interleaved mapping (e.g., for the purpose of providingfrequency diversity) or a non-interleaved mapping (e.g., for thepurposes of facilitating interference coordination and/orfrequency-selective transmission of control channels). The base stationmay perform different or same CCE-to-REG mapping on different CORESETs.A CORESET may be associated with a CCE-to-REG mapping by RRCconfiguration. A CORESET may be configured with an antenna port quasico-location (QCL) parameter. The antenna port QCL parameter may indicateQCL information of a demodulation reference signal (DMRS) for PDCCHreception in the CORESET.

The base station may transmit, to the UE, RRC messages comprisingconfiguration parameters of one or more CORESETs and one or more searchspace sets. The configuration parameters may indicate an associationbetween a search space set and a CORESET. A search space set maycomprise a set of PDCCH candidates formed by CCEs at a given aggregationlevel. The configuration parameters may indicate: a number of PDCCHcandidates to be monitored per aggregation level; a PDCCH monitoringperiodicity and a PDCCH monitoring pattern; one or more DCI formats tobe monitored by the UE; and/or whether a search space set is a commonsearch space set or a UE-specific search space set. A set of CCEs in thecommon search space set may be predefined and known to the UE. A set ofCCEs in the UE-specific search space set may be configured based on theUE's identity (e.g., C-RNTI).

As shown in FIG. 14B, the UE may determine a time-frequency resource fora CORESET based on RRC messages. The UE may determine a CCE-to-REGmapping (e.g., interleaved or non-interleaved, and/or mappingparameters) for the CORESET based on configuration parameters of theCORESET. The UE may determine a number (e.g., at most 10) of searchspace sets configured on the CORESET based on the RRC messages. The UEmay monitor a set of PDCCH candidates according to configurationparameters of a search space set. The UE may monitor a set of PDCCHcandidates in one or more CORESETs for detecting one or more DCIs.Monitoring may comprise decoding one or more PDCCH candidates of the setof the PDCCH candidates according to the monitored DCI formats.Monitoring may comprise decoding a DCI content of one or more PDCCHcandidates with possible (or configured) PDCCH locations, possible (orconfigured) PDCCH formats (e.g., number of CCEs, number of PDCCHcandidates in common search spaces, and/or number of PDCCH candidates inthe UE-specific search spaces) and possible (or configured) DCI formats.The decoding may be referred to as blind decoding. The UE may determinea DCI as valid for the UE, in response to CRC checking (e.g., scrambledbits for CRC parity bits of the DCI matching a RNTI value). The UE mayprocess information contained in the DCI (e.g., a scheduling assignment,an uplink grant, power control, a slot format indication, a downlinkpreemption, and/or the like).

The UE may transmit uplink control signaling (e.g., uplink controlinformation (UCI)) to a base station. The uplink control signaling maycomprise hybrid automatic repeat request (HARQ) acknowledgements forreceived DL-SCH transport blocks. The UE may transmit the HARQacknowledgements after receiving a DL-SCH transport block. Uplinkcontrol signaling may comprise channel state information (CSI)indicating channel quality of a physical downlink channel. The UE maytransmit the CSI to the base station. The base station, based on thereceived CSI, may determine transmission format parameters (e.g.,comprising multi-antenna and beamforming schemes) for a downlinktransmission. Uplink control signaling may comprise scheduling requests(SR). The UE may transmit an SR indicating that uplink data is availablefor transmission to the base station. The UE may transmit a UCI (e.g.,HARQ acknowledgements (HARQ-ACK), CSI report, SR, and the like) via aphysical uplink control channel (PUCCH) or a physical uplink sharedchannel (PUSCH). The UE may transmit the uplink control signaling via aPUCCH using one of several PUCCH formats.

There may be five PUCCH formats and the UE may determine a PUCCH formatbased on a size of the UCI (e.g., a number of uplink symbols of UCItransmission and a number of UCI bits). PUCCH format 0 may have a lengthof one or two OFDM symbols and may include two or fewer bits. The UE maytransmit UCI in a PUCCH resource using PUCCH format 0 if thetransmission is over one or two symbols and the number of HARQ-ACKinformation bits with positive or negative SR (HARQ-ACK/SR bits) is oneor two. PUCCH format 1 may occupy a number between four and fourteenOFDM symbols and may include two or fewer bits. The UE may use PUCCHformat 1 if the transmission is four or more symbols and the number ofHARQ-ACK/SR bits is one or two. PUCCH format 2 may occupy one or twoOFDM symbols and may include more than two bits. The UE may use PUCCHformat 2 if the transmission is over one or two symbols and the numberof UCI bits is two or more. PUCCH format 3 may occupy a number betweenfour and fourteen OFDM symbols and may include more than two bits. TheUE may use PUCCH format 3 if the transmission is four or more symbols,the number of UCI bits is two or more and PUCCH resource does notinclude an orthogonal cover code. PUCCH format 4 may occupy a numberbetween four and fourteen OFDM symbols and may include more than twobits. The UE may use PUCCH format 4 if the transmission is four or moresymbols, the number of UCI bits is two or more and the PUCCH resourceincludes an orthogonal cover code.

The base station may transmit configuration parameters to the UE for aplurality of PUCCH resource sets using, for example, an RRC message. Theplurality of PUCCH resource sets (e.g., up to four sets) may beconfigured on an uplink BWP of a cell. A PUCCH resource set may beconfigured with a PUCCH resource set index, a plurality of PUCCHresources with a PUCCH resource being identified by a PUCCH resourceidentifier (e.g., pucch-Resourceid), and/or a number (e.g. a maximumnumber) of UCI information bits the UE may transmit using one of theplurality of PUCCH resources in the PUCCH resource set. When configuredwith a plurality of PUCCH resource sets, the UE may select one of theplurality of PUCCH resource sets based on a total bit length of the UCIinformation bits (e.g., HARQ-ACK, SR, and/or CSI). If the total bitlength of UCI information bits is two or fewer, the UE may select afirst PUCCH resource set having a PUCCH resource set index equal to “0”.If the total bit length of UCI information bits is greater than two andless than or equal to a first configured value, the UE may select asecond PUCCH resource set having a PUCCH resource set index equal to“1”. If the total bit length of UCI information bits is greater than thefirst configured value and less than or equal to a second configuredvalue, the UE may select a third PUCCH resource set having a PUCCHresource set index equal to “2”. If the total bit length of UCIinformation bits is greater than the second configured value and lessthan or equal to a third value (e.g., 1406), the UE may select a fourthPUCCH resource set having a PUCCH resource set index equal to “3”.

After determining a PUCCH resource set from a plurality of PUCCHresource sets, the UE may determine a PUCCH resource from the PUCCHresource set for UCI (HARQ-ACK, CSI, and/or SR) transmission. The UE maydetermine the PUCCH resource based on a PUCCH resource indicator in aDCI (e.g., with a DCI format 1_0 or DCI for 1_1) received on a PDCCH. Athree-bit PUCCH resource indicator in the DCI may indicate one of eightPUCCH resources in the PUCCH resource set. Based on the PUCCH resourceindicator, the UE may transmit the UCI (HARQ-ACK, CSI and/or SR) using aPUCCH resource indicated by the PUCCH resource indicator in the DCI.

FIG. 15 illustrates an example of a wireless device 1502 incommunication with a base station 1504 in accordance with embodiments ofthe present disclosure. The wireless device 1502 and base station 1504may be part of a mobile communication network, such as the mobilecommunication network 100 illustrated in FIG. 1A, the mobilecommunication network 150 illustrated in FIG. 1B, or any othercommunication network. Only one wireless device 1502 and one basestation 1504 are illustrated in FIG. 15 , but it will be understood thata mobile communication network may include more than one UE and/or morethan one base station, with the same or similar configuration as thoseshown in FIG. 15 .

The base station 1504 may connect the wireless device 1502 to a corenetwork (not shown) through radio communications over the air interface(or radio interface) 1506. The communication direction from the basestation 1504 to the wireless device 1502 over the air interface 1506 isknown as the downlink, and the communication direction from the wirelessdevice 1502 to the base station 1504 over the air interface is known asthe uplink. Downlink transmissions may be separated from uplinktransmissions using FDD, TDD, and/or some combination of the twoduplexing techniques.

In the downlink, data to be sent to the wireless device 1502 from thebase station 1504 may be provided to the processing system 1508 of thebase station 1504. The data may be provided to the processing system1508 by, for example, a core network. In the uplink, data to be sent tothe base station 1504 from the wireless device 1502 may be provided tothe processing system 1518 of the wireless device 1502. The processingsystem 1508 and the processing system 1518 may implement layer 3 andlayer 2 OSI functionality to process the data for transmission. Layer 2may include an SDAP layer, a PDCP layer, an RLC layer, and a MAC layer,for example, with respect to FIG. 2A, FIG. 2B, FIG. 3 , and FIG. 4A.Layer 3 may include an RRC layer as with respect to FIG. 2B.

After being processed by processing system 1508, the data to be sent tothe wireless device 1502 may be provided to a transmission processingsystem 1510 of base station 1504. Similarly, after being processed bythe processing system 1518, the data to be sent to base station 1504 maybe provided to a transmission processing system 1520 of the wirelessdevice 1502. The transmission processing system 1510 and thetransmission processing system 1520 may implement layer 1 OSIfunctionality. Layer 1 may include a PHY layer with respect to FIG. 2A,FIG. 2B, FIG. 3 , and FIG. 4A. For transmit processing, the PHY layermay perform, for example, forward error correction coding of transportchannels, interleaving, rate matching, mapping of transport channels tophysical channels, modulation of physical channel, multiple-inputmultiple-output (MIMO) or multi-antenna processing, and/or the like.

At the base station 1504, a reception processing system 1512 may receivethe uplink transmission from the wireless device 1502. At the wirelessdevice 1502, a reception processing system 1522 may receive the downlinktransmission from base station 1504. The reception processing system1512 and the reception processing system 1522 may implement layer 1 OSIfunctionality. Layer 1 may include a PHY layer with respect to FIG. 2A,FIG. 2B, FIG. 3 , and FIG. 4A. For receive processing, the PHY layer mayperform, for example, error detection, forward error correctiondecoding, deinterleaving, demapping of transport channels to physicalchannels, demodulation of physical channels, MIMO or multi-antennaprocessing, and/or the like.

As shown in FIG. 15 , a wireless device 1502 and the base station 1504may include multiple antennas. The multiple antennas may be used toperform one or more MIMO or multi-antenna techniques, such as spatialmultiplexing (e.g., single-user MIMO or multi-user MIMO),transmit/receive diversity, and/or beamforming. In other examples, thewireless device 1502 and/or the base station 1504 may have a singleantenna.

The processing system 1508 and the processing system 1518 may beassociated with a memory 1514 and a memory 1524, respectively. Memory1514 and memory 1524 (e.g., one or more non-transitory computer readablemediums) may store computer program instructions or code that may beexecuted by the processing system 1508 and/or the processing system 1518to carry out one or more of the functionalities discussed in the presentapplication. Although not shown in FIG. 15 , the transmission processingsystem 1510, the transmission processing system 1520, the receptionprocessing system 1512, and/or the reception processing system 1522 maybe coupled to a memory (e.g., one or more non-transitory computerreadable mediums) storing computer program instructions or code that maybe executed to carry out one or more of their respectivefunctionalities.

The processing system 1508 and/or the processing system 1518 maycomprise one or more controllers and/or one or more processors. The oneor more controllers and/or one or more processors may comprise, forexample, a general-purpose processor, a digital signal processor (DSP),a microcontroller, an application specific integrated circuit (ASIC), afield programmable gate array (FPGA) and/or other programmable logicdevice, discrete gate and/or transistor logic, discrete hardwarecomponents, an on-board unit, or any combination thereof. The processingsystem 1508 and/or the processing system 1518 may perform at least oneof signal coding/processing, data processing, power control,input/output processing, and/or any other functionality that may enablethe wireless device 1502 and the base station 1504 to operate in awireless environment.

The processing system 1508 and/or the processing system 1518 may beconnected to one or more peripherals 1516 and one or more peripherals1526, respectively. The one or more peripherals 1516 and the one or moreperipherals 1526 may include software and/or hardware that providefeatures and/or functionalities, for example, a speaker, a microphone, akeypad, a display, a touchpad, a power source, a satellite transceiver,a universal serial bus (USB) port, a hands-free headset, a frequencymodulated (FM) radio unit, a media player, an Internet browser, anelectronic control unit (e.g., for a motor vehicle), and/or one or moresensors (e.g., an accelerometer, a gyroscope, a temperature sensor, aradar sensor, a lidar sensor, an ultrasonic sensor, a light sensor, acamera, and/or the like). The processing system 1508 and/or theprocessing system 1518 may receive user input data from and/or provideuser output data to the one or more peripherals 1516 and/or the one ormore peripherals 1526. The processing system 1518 in the wireless device1502 may receive power from a power source and/or may be configured todistribute the power to the other components in the wireless device1502. The power source may comprise one or more sources of power, forexample, a battery, a solar cell, a fuel cell, or any combinationthereof. The processing system 1508 and/or the processing system 1518may be connected to a GPS chipset 1517 and a GPS chipset 1527,respectively. The GPS chipset 1517 and the GPS chipset 1527 may beconfigured to provide geographic location information of the wirelessdevice 1502 and the base station 1504, respectively.

FIG. 16A illustrates an example structure for uplink transmission. Abaseband signal representing a physical uplink shared channel mayperform one or more functions. The one or more functions may comprise atleast one of: scrambling; modulation of scrambled bits to generatecomplex-valued symbols; mapping of the complex-valued modulation symbolsonto one or several transmission layers; transform precoding to generatecomplex-valued symbols; precoding of the complex-valued symbols; mappingof precoded complex-valued symbols to resource elements; generation ofcomplex-valued time-domain Single Carrier-Frequency Division MultipleAccess (SC-FDMA) or CP-OFDM signal for an antenna port; and/or the like.In an example, when transform precoding is enabled, a SC-FDMA signal foruplink transmission may be generated. In an example, when transformprecoding is not enabled, an CP-OFDM signal for uplink transmission maybe generated by FIG. 16A. These functions are illustrated as examplesand it is anticipated that other mechanisms may be implemented invarious embodiments.

FIG. 16B illustrates an example structure for modulation andup-conversion of a baseband signal to a carrier frequency. The basebandsignal may be a complex-valued SC-FDMA or CP-OFDM baseband signal for anantenna port and/or a complex-valued Physical Random Access Channel(PRACH) baseband signal. Filtering may be employed prior totransmission.

FIG. 16C illustrates an example structure for downlink transmissions. Abaseband signal representing a physical downlink channel may perform oneor more functions. The one or more functions may comprise: scrambling ofcoded bits in a codeword to be transmitted on a physical channel;modulation of scrambled bits to generate complex-valued modulationsymbols; mapping of the complex-valued modulation symbols onto one orseveral transmission layers; precoding of the complex-valued modulationsymbols on a layer for transmission on the antenna ports; mapping ofcomplex-valued modulation symbols for an antenna port to resourceelements; generation of complex-valued time-domain OFDM signal for anantenna port; and/or the like. These functions are illustrated asexamples and it is anticipated that other mechanisms may be implementedin various embodiments.

FIG. 16D illustrates another example structure for modulation andup-conversion of a baseband signal to a carrier frequency. The basebandsignal may be a complex-valued OFDM baseband signal for an antenna port.Filtering may be employed prior to transmission.

A wireless device may receive from a base station one or more messages(e.g. RRC messages) comprising configuration parameters of a pluralityof cells (e.g. primary cell, secondary cell). The wireless device maycommunicate with at least one base station (e.g. two or more basestations in dual-connectivity) via the plurality of cells. The one ormore messages (e.g. as a part of the configuration parameters) maycomprise parameters of physical, MAC, RLC, PCDP, SDAP, RRC layers forconfiguring the wireless device. For example, the configurationparameters may comprise parameters for configuring physical and MAClayer channels, bearers, etc. For example, the configuration parametersmay comprise parameters indicating values of timers for physical, MAC,RLC, PCDP, SDAP, RRC layers, and/or communication channels.

A timer may begin running once it is started and continue running untilit is stopped or until it expires. A timer may be started if it is notrunning or restarted if it is running. A timer may be associated with avalue (e.g. the timer may be started or restarted from a value or may bestarted from zero and expire once it reaches the value). The duration ofa timer may not be updated until the timer is stopped or expires (e.g.,due to BWP switching). A timer may be used to measure a timeperiod/window for a process. When the specification refers to animplementation and procedure related to one or more timers, it will beunderstood that there are multiple ways to implement the one or moretimers. For example, it will be understood that one or more of themultiple ways to implement a timer may be used to measure a timeperiod/window for the procedure. For example, a random access responsewindow timer may be used for measuring a window of time for receiving arandom access response. In an example, instead of starting and expiry ofa random access response window timer, the time difference between twotime stamps may be used. When a timer is restarted, a process formeasurement of time window may be restarted. Other exampleimplementations may be provided to restart a measurement of a timewindow.

In an example, a small data transmission (SDT) in a wireless network(e.g., LTE, 5G, new radio, NR, etc.) may be interpreted as an early datatransmission (EDT). The term of SDT and the term of EDT may beinterchangeable to each other. The early data transmission performedinitially for uplink data transmission may be called as a mobileoriginating early data transmission (MO-EDT), an uplink EDT, an uplinkSDT, a mobile originating SDT (MO-SDT), and/or the like. The early datatransmission performed initially for downlink data transmission (e.g.,initiated based on a paging procedure) may be called as a mobileterminating early data transmission (MT-EDT), a downlink EDT, a downlinkSDT, a mobile terminating SDT (MT-SDT), and/or the like.

In an example, MO-EDT may allow one uplink data transmission optionallyfollowed by at least one downlink data transmission during and/or aftera random access procedure. MO-EDT may be triggered when upper layersrequests establishment or resumption of an RRC connection for mobileoriginating data (e.g., may be not signaling or SMS) and/or uplink datasize may be less than or equal to a transport block (TB) size indicatedin system information. MO-EDT may not be used for data over a controlplane when using user plane cellular Internet of things (CIoT) EPS/5GSoptimizations. MO-EDT may be applicable to bandwidth reduced lowcomplexity (BL) UEs, UEs in enhanced coverage (e.g., coverageenhancement UE, CE UE), narrowband IoT (NB-IoT) UEs, and/or reducedcapability (RedCap) UEs.

In an example, MO-EDT for Control Plane CIoT EPS optimization and/orControl Plane CIoT 5GS Optimization may be characterized as followings.Uplink user data may be transmitted in a NAS message concatenated in ULRRCEarlyDataRequest message on CCCH. Downlink user data may beoptionally transmitted in a NAS message concatenated in DLRRCEarlyDataComplete message on CCCH. UE may not transition to RRCCONNECTED.

FIG. 17 shows an example of an MO-EDT procedure for Control Plane CIoTEPS optimization and/or Control Plane CIoT 5GS Optimization. Uponconnection establishment request for Mobile originating (MO) data fromupper layers, a UE may initiate an MO-EDT procedure and/or may select arandom access preamble configured for EDT. UE may perform a randomaccess procedure by sending the selected random access preamble. UE maysend an RRC Early Data Request message concatenating user data on CCCH.For EPS or 5GS if enabled in a cell a UE may indicate AS ReleaseAssistance Information (RAI). For EPS, an eNB or a gNB may initiate anS1-AP Initial UE message procedure to forward a NAS message and/orestablish an S1 connection. For 5GS, an ng-eNB or a gNB may initiate anNG-AP Initial UE message procedure to forward a NAS message. An (ng-)eNBor a gNB may indicate that the connection is triggered for EDT (and/orSDT).

For EPS, an MME may request an S-GW to re-activate EPS bearers for a UE.For 5GS, an AMF may determine a PDU session contained/indicated in a NASmessage from a UE. For EPS, an MME may send uplink data to an S-GW. For5GS, an AMF may send a PDU Session ID and/or uplink data to an SMFand/or the SMF may forward the uplink data to a UPF. For EPS, ifdownlink data are available, an S-GW may send the downlink data to anMME. For 5GS, if downlink data are available, a UPF may forward thedownlink data to an SMF and/or the SMF may forward the downlink data toan AMF. If downlink data are received from an S-GW and/or SMF, an MME oran AMF may forward the downlink data to an eNB/ng-eNB or a gNB via DLNAS Transport procedure and/or may indicate whether further data areexpected. In an example, an MME or an AMF may trigger a ConnectionEstablishment Indication procedure and/or may indicate whether furtherdata are expected. In an example, If no further data are expected, an(ng-)eNB or a gNB may send an RRCEarlyDataComplete message on CCCH tokeep a UE in RRC_IDLE or RRC_INACTIVE. If downlink data were received,the downlink data may be concatenated in the RRCEarlyDataCompletemessage.

For EPS, an S1 connection may be released and/or EPS bearers may bedeactivated. For 5GS, an AN release procedure is started. If an MME/AMFor an (ng-)eNB or gNB decides to move a UE in RRC_CONNECTED state, anRRCConnectionSetup message or an RRCResume message may be sent to fallback to an RRC Connection establishment/setup/resume procedure. An(ng-)eNB or gNB may discard a zero-length NAS PDU received inRRCConnectionSetupComplete message. If neither RRCEarlyDataComplete nor,in case of fallback, RRCConnectionSetup/establishment/resume is receivedin response to RRCEarlyDataRequest, a UE may considers an UL datatransmission is not successful.

In an example, MO-EDT for User Plane CIoT EPS optimization and/or UserPlane CIoT 5GS Optimization may be characterized as followings. A UE maybe provided with a NextHopChainingCount (NCC) in an RRCConnectionReleasemessage and/or an RRC release message with suspend indication. Uplinkuser data may be transmitted on DTCH multiplexed with an ULRRCConnectionResumeRequest message or an RRC resume request message onCCCH. Downlink user data may be optionally transmitted on DTCHmultiplexed with a DL RRCConnectionRelease message and/or an RRC releasemessage on DCCH. A short resume MAC-I (shortResumeMAC-I) may be reusedas an authentication token for RRCConnectionResumeRequest message and/orRRC resume request message. A short resume MAC-I may be calculated usingan integrity key from a previous connection. User data in uplink and/ordownlink may be ciphered. The keys may be derived using aNextHopChainingCount (NCC) provided in an RRCConnectionRelease messageand/or RRC release message of a previous RRC connection. AnRRCConnectionRelease message and/or an RRC release message may beintegrity protected and/or ciphered using newly derived keys. There maybe no transition to RRC CONNECTED from an RRC idle state and/or an RRCinactive state.

FIG. 18 shows an example of an MO-EDT procedure for User Plane CIoT EPSoptimization and/or User Plane CIoT 5GS Optimization. Upon connectionresumption request for Mobile originating data from upper layers, a UEmay initiate an MO-EDT procedure and/or may select a random accesspreamble configured for EDT. A UE may send an RRCConnectionResumeRequestto an eNB and/or a gNB, comprising a Resume ID, an establishment cause,and/or an authentication token. A UE may resume all SRBs and/or DRBs. AUE may resume some of SRBs and/or DRBs configured in a previous RRCconnection. A UE may derive new security keys using aNextHopChainingCount provided in an RRCConnectionRelease message of aprevious RRC connection and/or may re-establish an AS security. Userdata may be ciphered and/or transmitted via DTCH multiplexed with anRRCConnectionResumeRequest message on CCCH. If enabled in a cell, a UEmay indicate AS Release Assistance Information (RAI). An eNB mayinitiate an S1-AP Context Resume procedure to resume an S1 connectionand/or re-activate S1-U bearers. An MME may request an S-GW tore-activate S1-U bearers for a UE. An MME may confirm a UE contextresumption to an eNB. Uplink data may be delivered to an S-GW. Ifdownlink data are available, an S-GW may send the downlink data to aneNB. If no further data are expected, an eNB may initiate suspension ofan S1 connection and/or deactivation of S1-U bearers for a UE. An eNBmay send an RRCConnectionRelease message and/or an RRC release messageto keep a UE in RRC_IDLE state and/or RRC inactive state. AnRRCConnectionRelease message and/or an RRC release message may comprisea releaseCause set to rrc-Suspend, a resumeID, a NextHopChainingCount(NCC), and/or drb-ContinueROHC that may be stored by a UE. If downlinkdata is received, the downlink data may be sent ciphered via DTCHmultiplexed with an RRCConnectionRelease message and/or an RRC releasemessage via DCCH.

As shown in FIG. 18 , upon connection resumption request for Mobileoriginating data from the upper layers, a UE may initiate an MO-EDTprocedure and/or may select a random access preamble configured for EDT.A UE may send an RRCConnectionResumeRequest and/or an RRC resume requestmessage to an ng-eNB and/or a gNB, comprising an I-RNTI, a resume cause,and/or an authentication token. A UE may resume all SRBs and DRBs. A UEmay resume some of SRBs and/or DRBs configured in a previous RRCconnection. A UE may derive new security keys using aNextHopChainingCount (NCC) provided in an RRCConnectionRelease messageand/or an RRC release message of a previous connection and/or mayre-establish an AS security. User data may be ciphered and/ortransmitted via DTCH multiplexed with an RRCConnectionResumeRequestmessage and/or an RRC resume message on CCCH. A UE may indicate ASRelease Assistance Information (RAI). Uplink data may be delivered to anUPF. An ng-eNB and/or a gNB may send a NG-AP Context Resume Requestmessage to an AMF to resume a connection. If a UE included AS ReleaseAssistance information indicating No further UL/DL higher layer PDU, anng-eNB and/or a gNB may request for immediate transition to RRC IDLEwith Suspend and/or an RRC inactive state. If an AMF does not receive arequest for immediate transition to RRC IDLE with Suspend and/or an RRCinactive state or the AMF is aware of downlink data or signalingpending, the AMF may request an SMF to resume a PDU session. An AMF maysend an NG-AP Context Resume Response to a ng-eNB and/or a gNB. If anAMF receive a request for immediate transition to RRC IDLE with Suspendand/or an RRC inactive state and/or if there is no downlink data orsignaling pending, the AMF may include a Suspend indication. An AMF maykeep a UE in CM-IDLE with Suspend. If an AMF includes Suspendindication, an ng-eNB and/or a gNB may proceed an RRC release procedurewith suspend. If an AMF does not include Suspend indication and/or if aUE included AS Release Assistance information indicating a singleDownlink Data transmission subsequent to an Uplink transmission, anng-eNB and/or a gNB may wait for downlink data to arrive. An ng-eNBand/or a gNB may initiate an NG-AP UE Context Suspend procedure toinform an AMF that an RRC connection may be suspended. An AMF mayrequest an SMF to suspend a PDU session. An SMF may request a UPF torelease tunnel information for a UE. an eNB/ng-eNB and/or a gNB may sendan RRCConnectionRelease message and/or an RRC release message to keep aUE in RRC_IDLE and/or an RRC inactive state. An RRCConnectionReleasemessage and/or an RRC release message may comprise a releaseCause thatmay be set to rrc-Suspend, an I-RNTI, a NextHopChainingCount (NCC),and/or drb-ContinueROHC that may be stored by a UE. If downlink data(e.g., subsequent downlink data) are received, the downlink data may besent ciphered via DTCH multiplexed with an RRCConnectionRelease messageand/or an RRC release message on DCCH.

In an example, if an MME/AMF or (ng-)eNB/gNB decides a UE to move inRRC_CONNECTED state, RRCConnectionResume message and/or RRC resume/setupmessage may be sent to fall back to an RRC Connection resume procedure.An RRCConnectionResume message and/or an RRC resume/setup message may beintegrity protected and/or ciphered with keys derived. A UE may ignore aNextHopChainingCount (NCC) included in an RRCConnectionResume messageand/or an RRC resume message. Downlink data may be transmitted via DTCHmultiplexed with an RRCConnectionResume message and/or an RRCresume/setup message. An RRCConnectionSetup and/or an RRC setup messagemay be sent to fall back to an RRC Connection establishment/setupprocedure. In an example, if neither RRCConnectionRelease message (RRCrelease message) nor RRCConnectionResume message (RRC resume/setupmessage) is received in response to an RRCConnectionResumeRequestmessage and/or an RRC resume request message for MO-EDT, a UE mayconsider uplink data transmission not successful.

In an example, as shown in FIG. 19 , for MO-EDT for User Plane CIoT EPSOptimization and/or User Plane CIoT 5GS Optimization, an RRC connectionmay be resumed in an (ng-)eNB (e.g., new (ng-)eNB) and/or a gNB (e.g.,new gNB) different from a base station where an RRC connection wassuspended (old (ng-)eNB and/or old gNB). Inter (ng-)eNB or inter gNBconnection resumption may be handled using context fetching. A new(ng-)eNB or a new gNB may retrieve UE contexts from an old (ng-)eNBand/or an old gNB over an X2 (Xn) interface. A new (ng-)eNB or new gNBmay provide a Resume ID for EPS or I-RNTI for 5GS that may be used by anold (ng-)eNB or an old gNB to identify UE contexts of a UE.

FIG. 19 shows an example of an MO-EDT procedure for User Plane CIoT EPSoptimization and/or User Plane CIoT 5GS Optimization in a differenteNB/ng-eNB and/or a different gNB (e.g., base station relocation case).A new (ng-)eNB or a new gNB may locate/determine an old (ng-)eNB using aResume ID (e.g., for EPS) or I-RNTI (e.g., for 5GS) and/or may retrieveUE contexts by performing a Retrieve UE Context procedure via an X2-AP(for EPS) or an Xn-AP (for 5GS). An old (ng-)eNB may respond with UEcontexts associated with a Resume ID (e.g., for EPS) or I-RNTI (e.g.,for 5GS). For EPS, a new eNB or a new gNB may initiate an S1-AP PathSwitch procedure to establish an S1 UE associated signaling connectionto a serving MME and/or to request the MME to resume UE contexts. For5GS, a new ng-eNB or a new gNB may initiate an NG-AP Path Switchprocedure to establish a NG UE associated signaling connection to aserving AMF and/or to request the AMF to resume UE contexts. For EPS, anMME may request an S-GW to activate S1-U bearers for a UE and/or mayupdate a downlink path. For 5GS, an AMF may request an SMF to resume aPDU session. An SMF may request a UPF to create tunnel information for aUE and/or update a downlink path. For EPS, after an S1-AP Path Switchprocedure a new eNB and/or a new gNB may trigger release of UE contextsat an old eNB or an old gNB by performing a UE Context Release procedurevia an X2-AP. For 5GS, after an NG-AP Path Switch procedure a new ng-eNBand/or a new gNB may trigger release of UE contexts at an old ng-eNBand/or an old gNB by performing UE Context Release procedure via anXn-AP. Uplink data may be delivered to an S-GW and/or a UPF.

In an example, MT-EDT may be for a single downlink data transmissionduring a random access procedure. MT-EDT may be initiated by an MME, anAMF/SMF, or a gNB if a UE and/or a network supports MT-EDT and/or ifthere is a single DL data transmission for the UE. MT-EDT for ControlPlane CIoT EPS/5GS Optimization and/or for User Plane CIoT EPS/5GSOptimization may be characterized as followings. Support for MT-EDT forControl Plane CIoT EPS/5GS Optimization and/or for User Plane CIoTEPS/5GS Optimization may be reported by UE via NAS level signaling(e.g., via NAS message). Downlink data size may be included/indicated inan S1-AP or NG-AP Paging message for a UE. MT-EDT indication may beincluded in a Paging message for a UE over a Uu interface. For UserPlane CIoT EPS/5GS Optimization, a UE may be provided with aNextHopChainingCount (NCC) in an RRCConnectionRelease message and/or anRRC release message with suspend indication. In response to a Pagingmessage including/comprising MT-EDT indication, a UE may trigger anMO-EDT procedure for Control Plane CIoT EPS/5GS Optimization or for UserPlane CIoT EPS/5GS Optimization if upper layers request establishment orresumption of an RRC Connection for Mobile Terminated Call. UEperforming an MT-EDT may not transition to an RRC CONNECTED state.MT-EDT may be applicable to BL UEs, UEs in enhanced coverage (e.g., CEUE), and/or NB-IoT UEs.

In an example, transmission using preconfigured uplink resource (PUR)may allow at least one uplink transmission from RRC_IDLE (RRC idlestate) and/or RRC_INACTIVE (RRC inactive state) using a PUR withoutperforming the random access procedure. Transmission using PUR may beenabled by an (ng-)eNB and/or a gNB if the UE and/or the (ng-)eNBsupport.

In an example, a UE may request to be configured with a PUR and/or tohave a PUR configuration released while in RRC_CONNECTED mode/state. The(ng-)eNB/gNB may decide to configure a PUR that may be based on UE'srequest, UE's subscription information, and/or local policy. The PUR maybe valid in the cell where the configuration was received.

Transmission using PUR may be triggered when upper layers of UE requestestablishment or resumption of an RRC Connection. Transmission using PURmay be triggered when a UE has data to transmit. Transmission using PURmay be triggered when a UE has a valid PUR for transmission and/or meetsa TA validation criteria. Transmission using PUR may be applicable to BLUEs, UEs in enhanced coverage, and/or NB-IoT UEs. FIG. 23 shows anexample of transmission using PUR.

In an example, as shown in FIG. 20 , a procedure for PUR configurationrequest and/or PUR configuration may be used for a Control Plane CIoTEPS/5GS optimizations and/or a User Plane CIoT EPS/5GS optimizations. AUE may send PUR configuration request to a base station (e.g., gNB,eNB). The base station may send an RRC connection release indication andPUR configuration parameters to the UE. The PUR configuration parametersmay be based on the PUR configuration request. In an example, as shownin FIG. 20 , a UE may be in RRC_CONNECTED and a PUR may be enabled in acell. The UE may indicate to a (ng-)eNB or gNB that the UE is interestedin being configured with PUR by sending PUR Configuration Requestmessage providing information about the requested resource (e.g., numberof occurrences, periodicity, time offset, TBS, RRC Ack, etc.). The UEmay indicate to the (ng-)eNB or gNB in the PURConfigurationRequestmessage that the UE is interested in the configured PUR to be released.When the (ng-)eNB or gNB moves the UE to RRC_IDLE or RRC_INACTIVE (e.g.,based on a precedent UE PUR configuration request, subscriptioninformation, and/or local policies) the (ng-)eNB or gNB may decide toprovide a PUR resource to the UE or to release an existing PUR resource.The (ng-)eNB or gNB may include parameters of the PUR configuration or aPUR release indication in the RRC Connection Release message. For UEsusing the Control Plane CIoT EPS/5GS optimizations, the (ng-)eNB or gNBmay provide a PUR configuration ID with the PUR configuration. Ifavailable, the UE may include the PUR configuration ID in RRC ConnectionSetup/Resume Complete message when establishing/resuming RRCconnection(s) not using the PUR resource.

In an example, the PUR configuration may be released at the UE and/or(ng-) eNB/gNB, when the UE accesses in another cell, when PUR is nolonger enabled in the cell, and/or when the PUR resource has not beenused for a configured number of consecutive occasions. In an example, aUE and PUR configuration may be linked according to configured PURresources.

In an example, FIG. 21 shows an example of transmission using PUR forControl Plane CIoT EPS Optimization and/or for Control Plane CIoT 5GSOptimization. Uplink user data may be transmitted using the PUR resourcein a NAS message concatenated in RRC Early Data Request message on CCCH.If there is no downlink data, the (ng-)eNB or gNB may terminate theprocedure by sending a layer 1 acknowledgement optionally containing aTime Advance Command, a MAC Time advance Command, and/or RRC Early DataComplete with no user data. Downlink user data may be transmitted in aNAS message concatenated in RRC Early Data Complete message on CCCH. AUE may not transition to RRC CONNECTED.

In FIG. 21 , a UE may determine that the PUR resource can be used (e.g.,PUR enabled in the cell, valid Time Alignment, etc.). The UE maytransmit over the PUR resource. If the uplink data are too large to beincluded in RRC Early Data Request, the UE may use the PUR resource totransmit RRC Connection Request. The procedure may fall back to an RRCConnection establishment procedure and/or a new C-RNTI may be assigned.The (ng-)eNB or gNB may request the UE to abort the transmission usingPUR by sending a Layer 1 fallback indication. In an example, for EPS,the eNB or gNB may initiate the S1-AP or N2/3 Initial UE messageprocedure to forward the NAS message and/or may establish the S1 orN2/N3 connection. For 5GS, the ng-eNB or gNB may initiate the NG-APInitial UE message procedure to forward the NAS message. The (ng-)eNB orgNB may indicate that this connection is triggered for EDT. In anexample, for EPS, the MME may requests the S-GW to re-activate the EPSbearers for the UE. For 5GS, the AMF may determine the PDU sessioncontained in the NAS message. For EPS, the MME may send the uplink datato the S-GW. For 5GS, the AMF may send the PDU Session ID and/or theuplink data to the SMF. The SMF may forward the uplink data to the UPF.In an example, for EPS, if downlink data are available, the S-GW maysend the downlink data to the MME. For 5GS, if downlink data areavailable, the UPF may forward the downlink data to SMF. The SMF mayforward the downlink data to AMF. If downlink data are received from theS-GW or SMF, the MME or AMF may forward the data to the eNB/ng-eNB orgNB via DL NAS Transport procedure and/or may indicate whether furtherdata are expected. In an example, the MME or AMF may trigger ConnectionEstablishment Indication procedure and/or may indicate whether furtherdata are expected. If the (ng-)eNB or gNB is aware that there is nofurther data or signaling, the (ng-)eNB or gNB may send a Time AdvanceCommand to update the TA and/or terminate the procedure. In an example,if no further data are expected, the (ng-)eNB or gNB may send the RRCEarly Data Complete message on CCCH to keep the UE in RRC_IDLE orRRC_INACTIVE. If downlink data were received, the downlink data may beconcatenated in RRC Early Data Complete message. In an example, If theMME/AMF or the (ng-)eNB/gNB decides to move the UE to RRC_CONNECTEDmode, RRC Connection Setup message may be sent to fall back to the RRCConnection establishment procedure and/or a new C-RNTI may be assigned.The (ng-)eNB or gNB may discard a zero-length NAS PDU received in RRCConnection Setup Complete message. In an example, if none of Layer 1Ack, MAC Time advance Command, RRC Early Data Complete, and/or, in caseof fallback, RRC Connection Setup is received in response to RRC EarlyData Request, the UE may consider the UL data transmission notsuccessful.

In an example, as shown in FIG. 22 , a UE may transmit data using PURfor User Plane CIoT EPS Optimization and/or for User Plane CIoT 5GSOptimization. The UE may be in RRC_IDLE or RRC_INACTIVE and/or has avalid PUR resource. The UE may be provided with a Next Hop ChainingCount in the RRC Connection Release message with suspend indication.Uplink user data may be transmitted on DTCH multiplexed with RRCConnection Resume Request message on CCCH. Downlink user data may beoptionally transmitted on DTCH multiplexed with RRC Connection Releasemessage on DCCH. The user data in uplink and downlink may be ciphered.The keys may be derived using the Next Hop Chaining Count provided inthe RRC Connection Release message of the previous RRC connection. TheRRC Connection Release message may be integrity protected and/orciphered using the newly derived keys. The UE may not transition to RRCCONNECTED. In an example, the UE may transmit data using PUR for theUser Plane CIoT EPS optimization and for the User Plane CIoT 5GSoptimization.

In FIG. 22 , the UE may validate the PUR resource according to theconfigured criteria (e.g., TA validation, RSRP validation, etc.). In anexample, the UE may transmit over the PUR resource instead of a resourceallocated in the random access response. The UE may send an RRCConnection Resume Request to the eNB or gNB, including its Resume ID,the establishment cause, and/or an authentication token. The UE mayresume SRBs and DRBs. The UE may derive new security keys using theNextHopChainingCount provided in the RRC Connection Release message ofthe previous RRC connection and/or may re-establish the AS security. Theuser data may be ciphered and/or transmitted on DTCH multiplexed withthe RRC Connection Resume Request message on CCCH. If enabled in thecell, the UE may indicate AS Release Assistance Information. The UE maysend an RRCConnectionResumeRequest to the ng-eNB or gNB, including itsI-RNTI, the resume cause, and/or an authentication token. The UE mayresume SRBs and DRBs. The UE may derive new security keys using the NextHop Chaining Count provided in the RRC Connection Release message of theprevious connection and re-establishes the AS security. The user datamay be ciphered and transmitted on DTCH multiplexed with the RRCConnection Resume Request message on CCCH. The UE may indicate ASRelease Assistance Information. If the user data are too large to beincluded in the transmission using PUR, the UE may use PUR to transmitRRC Connection Resume Request and a segment of the user data. Theprocedure may be fall back to the RRC Connection Resume procedure. A newC-RNTI may be assigned. The (ng-)eNB or gNB may request the UE to abortthe transmission using PUR by sending a Layer 1 fallback indication.

In an example, the eNB or gNB may initiate the S1-AP Context Resumeprocedure to resume the S1 connection and re-activate the S1-U bearers.The MME may request the S-GW to re-activate the S1-U bearers for the UE.The MME may confirm the UE context resumption to the eNB or gNB. Theuplink data may be delivered to the S-GW. If downlink data areavailable, the S-GW may send the downlink data to the eNB or gNB. If nofurther data are expected, the eNB or gNB may initiate the suspension ofthe S1 connection and/or the deactivation of the S1-U bearers.

In an example, the uplink data may be delivered to the UPF. The ng-eNBor gNB may send a NG-AP Context Resume Request message to the AMF toresume the connection. If the UE included AS Release Assistanceinformation indicating No further UL/DL higher layer PDU, ng-eNB or gNBmay request for immediate transition to RRC_IDLE with Suspend and/orRRC_INACTIVE. In an example, If the AMF does not receive a request forimmediate transition to RRC IDLE with Suspend or the AMF is aware ofdownlink data or signaling pending, the AMF may request the SMF toresume the PDU session. The AMF may send a NG-AP Context Resume Responseto the ng-eNB or gNB. If the AMF receives a request for immediatetransition to RRC IDLE with Suspend and/or there is no downlink data orsignaling pending, the AMF may include a Suspend indication and/or maykeep the UE in CM-IDLE with Suspend. In an example, if the AMF does notinclude Suspend indication and/or the UE included AS Release Assistanceinformation indicating Only a single Downlink Data transmissionsubsequent to the Uplink transmission, the ng-eNB or gNB may wait forthe DL data to arrive. The ng-eNB or gNB may initiate the NG-AP UEContext Suspend procedure to inform the AMF that the RRC connection isbeing suspended. The AMF may request the SMF to suspend the PDU session.The SMF may request the UPF to release the tunnel information for theUE.

The eNB or gNB may send the RRCConnectionRelease message to keep the UEin RRC_IDLE. The message includes the releaseCause set to rrc-Suspend,the resumeID, the I-RNTI, the NextHopChainingCount and drb-ContinueROHCwhich are stored by the UE. If downlink data were received, the downlinkdata may be sent ciphered on DTCH multiplexed with theRRCConnectionRelease message on DCCH. In an example, the RRC connectionrelease message may include the Time Advance Command.

In an example, if the MME/AMF or the (ng-)eNB/gNB decides to move the UEto RRC_CONNECTED mode, RRC Connection Resume message may be sent to fallback to the RRC Connection resume procedure. The RRC Connection Resumemessage may be integrity protected and/or ciphered with the keys. The UEmay ignore the Next Hop Chaining Count included in the RRC ConnectionResume message. A new C-RNTI may be assigned. Downlink data may betransmitted on DTCH multiplexed with the RRC Connection Resume message.An RRC Connection Setup may be also be sent to fall back to the RRCConnection establishment procedure. If neither RRC Connection Releasenor, in case of fallback, RRC Connection Resume is received in responseto RRC Connection Resume Request using PUR, the UE may consider the ULdata transmission not successful.

In an example, transmission using PUR may be initiated by the RRC layer.When transmission using PUR is initiated, RRC layer may provide MAC withat least one of: PUR-RNTI, duration of PUR response windowpur-ResponseWindowSize, and/or UL grant information. In an example, Ifthe MAC entity has a PUR-RNTI, for TTI for which RRC layer provideduplink grant for transmission using PUR, the MAC entity may deliver theuplink grant and/or the associated HARQ information to the HARQ entityfor this TTI. After transmission using PUR, the MAC entity may monitorPDCCH identified by PUR-RNTI in the PUR response window using timerpur-ResponseWindowTimer. The PUR response window may start at thesubframe/slot/symbol that contains the end of the corresponding PUSCHtransmission plus 4 subframes/slot/symbol. The PUR response window mayhave the length pur-ResponseWindowSize. While pur-ResponseWindowTimer isrunning, the MAC entity may restart pur-ResponseWindowTimer at the lastsubframe/slot/symbol of a PUSCH transmission corresponding to theretransmission indicated by the UL grant plus 4 subframes/slots/symbolsif the PDCCH transmission is addressed to the PUR-RNTI and contains anUL grant for a retransmission. If L1 ACK for transmission using PUR isreceived from lower layers and/or if PDCCH transmission is addressed tothe PUR-RNTI and the MAC PDU is successfully decoded, the MAC entity maystop pur-ResponseWindowTimer. If L1 ACK for transmission using PUR isreceived from lower layers and/or the MAC PDU contains only TimingAdvance Command MAC control element, the MAC entity may indicate toupper layers the transmission using PUR was successful and/or maydiscard the PUR-RNTI. If repetition adjustment for transmission usingPUR is received from lower layers, the MAC entity may indicate the valueof the repetition adjustment to upper layers. In an example, if fallbackindication for PUR is received from lower layers, the MAC entity maystop pur-ResponseWindowTimer and/or may indicate to upper layers thatPUR fallback indication is received and/or may discard the PUR-RNTI. Ifrepetition adjustment for transmission using PUR is received from lowerlayers, the MAC entity may indicate the value of the repetitionadjustment to upper layers. If the pur-ResponseWindowTimer expires, theMAC entity may indicate to upper layers the transmission using PUR hasfailed and/or discard the PUR-RNTI.

In an example, the MAC entity may maintain timer pur-TimeAlignmentTimerby upper layers (e.g., RRC layer). In an example, the MAC entity maystart pur-TimeAlignmentTimer when pur-TimeAlignmentTimer configurationis received from upper layers. In an example, the MAC entity may stopthe pur-TimeAlignmentTimer when pur-TimeAlignmentTimer is released byupper layers. In an example, the MAC entity may apply the Timing AdvanceCommand or the timing advance adjustment and/or may start/restart thepur-TimeAlignmentTimer when a Timing Advance Command MAC control elementis received or PDCCH indicates timing advance adjustment. In an example,upon request from upper layers, MAC entity may indicate whetherpur-TimeAlignmentTimer is running.

In an example, a UE may consider the timing alignment value fortransmission using PUR to be valid when pur-TimeAlignmentTimer isrunning as confirmed by lower layers if pur-TimeAlignmentTimer isconfigured. In an example, a UE may consider the timing alignment valuefor transmission using PUR to be valid when, since the last TAvalidation, the serving cell RSRP has not increased by more thanincreaseThresh and/or the serving cell RSRP has not decreased by morethan decreaseThresh if pur-RSRP-ChangeThreshold(pur-NRSRP-ChangeThreshold in NB-IoT) is configured.

In an example, a UE configured with pur-Config may consider that thefirst PUR occasion occurs at the H-SFN/SFN/subframe given by H-SFNand/or SFN and subframe indicated by startSFN and startSubframe. H-SFNmay be determined based on (H-SFNRef+offset) mod 1024 occurring afterFLOOR (offset/1024) H-SFN cycles. The offset may be given byperiodicityAndOffset. H-SFNRef may correspond to the last subframe ofthe first transmission of RRC Connection Release message containingpur-Config, taking into account hsfn-LSB-Info. H-SFN cycle maycorrespond to a duration of 1024 H-SFNs.

In an example, in case that a pur-NumOccasions is set to one, for thefirst PUR occasion, if transmission using PUR is not initiated or iftransmission using PUR has been initiated, after the completion of thetransmission using PUR the UE may release pur-Config, may discardpreviously stored pur-Config, and/or may indicate to lower layers thatpur-TimeAlignmentTimer is released (e.g., if pur-TimeAlignmentTimer isconfigured).

In an example, in case that a pur-NumOccasions is not set to one (e.g.,periodic PUR configured) as shown in FIG. 23 , a UE may consider thatsubsequent PUR occasions occur periodically after an occurrence of thefirst PUR occasion at the SFN/subframe indicated by startSubframe andstartSFN and periodicity given by periodicityAndOffset. In case that apur-ImplicitReleaseAfter is configured, for a PUR occasion occurringwhile the UE is in RRC_IDLE or RRC_INACTIVE, if transmission using PURis not initiated or if PUR failure indication is received from lowerlayers, the UE may consider the PUR occasion as skipped. Ifpur-ImplicitReleaseAfter number of consecutive PUR occasions have beenskipped, the UE may release pur-Config, may discard previously storedpur-Config, and/or may indicate to lower layers thatpur-TimeAlignmentTimer is released if pur-TimeAlignmentTimer isconfigured.

In existing technologies, a wireless device in an RRC idle state or anRRC inactive state may perform a small data transmission (e.g., an earlydata transmission) to transmit uplink data and/or to receive downlinkdata. When a base station is split into a base station distributed unitand a base station central unit, a wireless device performing the smalldata transmission may transmit an RRC request message for the small datatransmission to the base station central unit and may transmit, to thebase station distributed unit, release assistance information indicatingwhether subsequent downlink or uplink data is expected.

In an example implementation of existing technologies, a base stationdistributed unit may determine, based on the release assistanceinformation, to complete the small data transmission of a wirelessdevice (e.g., perform an RRC release procedure) without transitioningthe wireless device to an RRC connected state. The determination of thebase station distributed unit to perform an RRC release procedure forthe wireless device may cause additional signaling to resume/establishan RRC connection of the wireless device if upper layers of a basestation needs more communication with the wireless device.

In an example implementation of existing technologies, a base stationcentral unit may determine, based on upper layer status or requirements,to complete the small data transmission of a wireless device (e.g.,perform an RRC release procedure) without transitioning the wirelessdevice to an RRC connected state. The determination of the base stationcentral unit to perform an RRC release procedure for the wireless devicemay cause additional signaling to resume/establish an RRC connection ofthe wireless device if subsequent uplink or downlink data for thewireless device is coming, as shown in FIG. 25 .

Existing technologies for small data transmission may increaseinefficient signaling. In an example implementation of existingtechnologies, a base station central unit may determine, based on upperlayer status, to transition a wireless device performing a small datatransmission to an RRC connected state. The determination of the basestation central unit to transition the wireless device to the RRCconnected state may make the wireless device to unnecessarily stay inthe RRC connected state when no subsequent uplink or downlink data forthe wireless device is expected, as shown in FIG. 26 . Existingtechnologies for small data transmission may increase inefficient statetransition of a wireless device.

In example embodiments, a base station distributed unit may send, to abase station central unit, assistance information for a small datatransmission (SDT) procedure of a wireless device. The base stationcentral unit may determine whether to transition the wireless device toan RRC connected state (e.g., by sending an RRC message indicatingtransition to the RRC connected state) or to complete the SDT procedureof the wireless device without transitioning the wireless device to anRRC connected state (e.g., send an RRC release message, perform an RRCrelease procedure, etc.). The determination may be based on theassistance information. The assistance information may indicate whethersubsequent data associated with the SDT procedure is expected. Forexample, the assistance information may comprise a buffer status reportof a wireless device performing the SDT procedure. For example, theassistance information may indicate a bearer that is associated with theSDT procedure. The base station central unit may determine to transitionthe wireless device to an RRC connected state, for example, if theassistance information indicates that one or more subsequent dataexpected, if data size indicated in the buffer status report is large,and/or if the bearer indicated in the assistance information needs thewireless device to transition to the RRC connected state. Exampleembodiments may reduce inefficient signaling. Example embodiments maydecrease inefficient state transition of a wireless device.

In an example, as shown in FIG. 27 , a wireless device (UE) maycommunicate with a base station (gNB) comprising a base station centralunit (gNB-CU) and a base station distributed unit (gNB-DU). The wirelessdevice may directly communicate with the base station distributed unitvia wireless channels of one or more cells comprising a cell (Cell1).The wireless device may communicate with the base station central unitvia the base station distributed unit. The base station distributed unitand the base station central unit may be connected to each other via anF1 interface comprising an F1 control plane interface (F1-C) and/or anF1 user plane interface (F1-U). The base station central unit maycomprise a base station central unit control plane (gNB-CU-CP) and/or abase station central unit user plane (gNB-CU-UP). The base stationdistributed unit may communicate with the base station central unitcontrol plane via the F1 control plane interface (F1-C). The basestation distributed unit may communicate with the base station centralunit user plane via the F1 user plane interface (F1-U). The base stationcentral unit control plane may communicate with the base station centralunit user plane via an E1 interface. In an example, the base station maycomprise a plurality of base station distributed units comprising thebase station distributed unit and/or a second base station distributedunit. The base station central unit may communicate with the pluralityof base station distributed units via a plurality of F1 interfaces. Thewireless device may communicate with the plurality of base stationdistributed units. The wireless device may communicate with the basestation central unit via one or more of the plurality of base stationdistributed units. In an example, the base station distributed unit orthe second base station distributed unit may provide a primary celland/or a master cell group for the wireless device. In an example, thebase station (e.g., the base station central unit, the base stationcentral unit control plane, and/or the base station central unit userplane) may be connected to a core network node/device (e.g., corenetwork control plane: AMF, MME; or core network user plane: UPF, S-GW).In an example, the base station (e.g., the base station central unit,the base station central unit control plane, and/or the base stationcentral unit user plane) may be connected to a plurality of neighboringbase stations comprising a second base station (e.g., gNB, eNB, etc.).In an example, the FIG. 24 shows a flow diagram of an example procedureof the small data transmission (e.g., the early data transmission) ofthe wireless device when the base station comprises the base stationdistributed unit and the base station central unit that may comprise thebase station central unit control plane and the base station centralunit user plane.

In an example, as shown in FIG. 27 and/or FIG. 28 , the base stationdistributed unit (gNB-DU) may receive, from the wireless device (UE), anRRC request message for a small data transmission (e.g., early datatransmission), uplink data, and/or at least one assistance parameterindicating whether at least one subsequent data transmission isexpected. The base station distributed unit may send, to the basestation central unit (gNB-CU), at least one message comprising the RRCrequest message for the small data transmission and/or assistanceinformation for initiation of an RRC release procedure for the wirelessdevice. The assistance information may be based on the at least oneassistance parameter. The assistance information may comprise at leastone first information element indicating whether at least one subsequentdata transmission is expected. The assistance information may compriseat least one second information element indicating/requesting whether toinitiate the RRC release procedure for the wireless device. The basestation central unit may receive, from the base station distributedunit, the at least one message comprising the RRC request message and/orthe assistance information. The base station central unit may receiveand/or forward the uplink data and/or subsequent uplink or downlinkdata. The base station central unit may determine, based on the at leastone message, whether to initiate the RRC release procedure for thewireless device. Based on the determining, the base station central unitmay send, to the wireless device, an RRC release message for the RRCrelease procedure or an RRC message for the wireless device totransition to an RRC connected state. The base station distributed unitmay receive, from the base station central unit, a context messagecomprising the RRC release message or the RRC message for the wirelessdevice. The base station distributed unit may transmit, to the wirelessdevice, the RRC release message or the RRC message.

In an example, the base station distributed unit (gNB-DU) may receive,from the wireless device (UE), the RRC request message for the smalldata transmission (e.g., early data transmission), uplink data, at leastone assistance parameter (e.g., release assistance information, RAI)indicating whether at least one subsequent data transmission isexpected, and/or the like. The wireless device may send, to the basestation and/or the base station distributed unit of the base station,the RRC request message. The uplink data and/or the at least oneassistance parameter may be multiplexed and/or concatenated with the RRCrequest message. In an example, the wireless device may receive, fromthe base station distributed unit, a paging message indicating a mobileterminating early data transmission (MT-EDT; e.g., mobile terminatingsmall data transmission). The wireless device may send the RRC messagefor the small data transmission based on the paging message, forexample, to receive downlink data associated with the MT-EDT.

In an example, the RRC request message may comprise at least one of: anRRC early data transmission request message, an RRC resume requestmessage, an RRC setup request message, and/or the like. In an example,the RRC request message may comprise at least one of a resume identifier(e.g., resumeIdentity, I-RNTI, shortI-RNTI), a resume MAC-I (e.g.,resumeMAC-I, shortResumeMAC-I), a resume cause, an S-TMSI (e.g., UEidentifier, NG-5G-S-TMSI), an establishment cause, a NAS layerinformation (e.g., NAS PDU, DedicatedInfoNAS), and/or the like. In anexample, the resume identifier may comprise a UE identity to facilitateUE context retrieval of the wireless device at a base station. In anexample, the resume MAC-I may comprise an authentication token tofacilitate authentication of the wireless device at a base station(e.g., 16 least significant bits of MAC-I may be calculated based on ASsecurity configuration). In an example, the resume cause may comprise atleast one of emergency, high priority access, mobile terminating access(mt-Access), mobile originating signaling (mo-Signaling), mobileoriginating data (mo-Data), delay tolerant access, mobile originatingvoice call (mo-VoiceCall), mobile terminating early data transmission(mt-EDT, MT SDT), mobile originating early data transmission (mo-EDT, MOSDT), RAN notification area update (ma-Update), and/or the like. Theresume cause may provide cause of an RRC resume request as provided byupper layers or RRC layer. A network may not reject an RRCResumeRequestdue to unknown cause value being used by the wireless device. In anexample, the establishment cause may comprise at least one of mobileoriginating data (mo-Data), delay tolerant access, mobile terminatingaccess (mt-Access), and/or the like. The establishment cause may providecause for an RRC early data request as provided by upper layers. Anetwork may not reject a RRCEarlyDataRequest due to unknown cause valuebeing used by the wireless device.

In an example, the small data transmission may comprise transmission ofat least one of: an initial uplink data, an initial downlink data (e.g.,the downlink data associated with the MT-EDT), at least one subsequentdata of the at least one subsequent data transmission indicated in theat least one assistance parameter, at least one subsequent uplink data,at least one subsequent downlink data, and/or the like. In an example,the at least one subsequent data transmission may be associated with thesmall data transmission. The at least one subsequent data transmissionmay comprise at least one of at least one subsequent uplink datatransmission, at least one subsequent downlink data transmission, and/orthe like.

In an example, the receiving by the base station distributed unit theRRC request message may comprise receiving the RRC request message basedon a random access process of the wireless device. In an example, thebase station distributed unit may receive, from the wireless device, atleast one random access preamble for the random access process. The basestation distributed unit may transmit, to the wireless device, at leastone random access response responding to the at least one random accesspreamble. The RRC request message may be based on the at least onerandom access response. The wireless device may transmit the RRC requestmessage based on the at least one random access response.

In an example, the at least one random access preamble for the randomaccess process associated with reception of the RRC request message maybe configured for the small data transmission. In an example, the basestation distributed unit may receive, from the base station centralunit, a configuration message comprising at least one RA parameterindicating the at least one random access preamble for the small datatransmission. The base station distributed unit may transmit/broadcast,to a plurality of wireless devices comprising the wireless device viathe cell of the base station distributed unit, a system informationblock indicating the at least one random access preamble for the smalldata transmission. The system information block may comprise the atleast one RA parameter indicating the at least one random accesspreamble for the small data transmission. The receiving by the basestation distributed unit the at least one random access preamble may bebased on the system information block. The wireless device may receivethe at least one information block and/or may transmit the at least onerandom access preamble based on the system information block. In anexample, the wireless device may receive the at least one RA parameterindicating the at least one random access preamble via an RRC releasemessage that the wireless device received when releasing/suspending aprevious RRC connection. The wireless device may receive the RRC releasemessage comprising the at least one RA parameter from the base stationand/or the base station distributed unit of the base station.

In an example, the receiving by the base station distributed unit theRRC request message may comprise receiving the RRC request message viaat least one preconfigured uplink resource (PUR). The wireless devicemay receive PUR configuration parameters for the at least one PUR via asystem information block and/or a downlink RRC message (e.g., RRCrelease message) from the base station and/or the base stationdistributed unit of the base station. The wireless device may transmitthe RRC request message, the uplink data, and/or the at least oneassistance parameter via the at least one PUR during a time that thewireless device is in an RRC idle state or an RRC inactive state. The atleast one PUR may comprise one or more periodic radio resources and/or asingle time resource.

The receiving the at least one assistance parameter may comprisereceiving the at least one assistance parameter via at least one of: atleast one medium access control element (MAC CE), a physical uplinkchannel (e.g., PUSCH, PUCCH, uplink control information, UCI), at leastone radio link control (RLC) packet header, and/or the like. In anexample, the wireless device may transmit, to the base stationdistributed unit, the at least one assistance parameter via the at leastone MAC CE multiplexed and/or concatenated with the RRC message and/orthe uplink data.

In an example, the at least one assistance parameter may comprise atleast one of: a parameter indicating no release assistance information(e.g., no RAI); a parameter indicating no subsequent downlink datatransmission is expected; a parameter indicating no subsequent uplinkdata transmission is expected; a parameter indicating a singlesubsequent downlink data transmission is expected; a parameterindicating a single subsequent uplink data transmission is expected; afirst number of subsequent downlink data transmission that is expected;a second number of subsequent uplink data transmission that is expected;and/or the like.

In an example, the at least one assistance parameter may comprise abuffer status report of the wireless device. The buffer status reportmay indicate size of data to transmit. The buffer status report mayindicate size of data associated with the small data transmission, thedata that may be buffered in at least one queue of the wireless device(e.g., MAC layer). The buffer status report may comprise at least onelogical channel identifier (LCID) of at least one logical channel and/orat least one logical channel group identifier (LCG ID) of at least onelogical channel group. The at least one logical channel and/or the atleast one logical channel group may be configured for data of the smalldata transmission. In an example, the at least one assistance parametermay comprise at least one of: a bearer identifier of a bearer, a logicalchannel identifier of a logical channel, a logical channel groupidentifier of a logical channel group, a QoS flow identifier of a QoSflow, a session identifier of a PDU session, and/or the like. Thebearer, the logical channel, the logical channel group, the QoS flow,the PDU session may be configured for data associated with the smalldata transmission.

In an example, the base station distributed unit mayconstruct/determine, based on the at least one assistance parameter, atleast one first information element (IE) of the assistance information.The at least one first information element may indicate whether at leastone subsequent data transmission is expected by the wireless device. Theat least one first information element may be an information element ofan F1 message. The at least one first information element may be atleast one parameter of a GTP protocol layer.

In an example, the at least one first information element may compriseat least one of: a parameter indicating no release assistanceinformation, a parameter indicating no subsequent downlink datatransmission is expected, a parameter indicating no subsequent uplinkdata transmission is expected, a parameter indicating a singlesubsequent downlink data transmission is expected, a parameterindicating a single subsequent uplink data transmission is expected; afirst number of subsequent downlink data transmission expected, a secondnumber of subsequent uplink data transmission expected, and/or the like.

In an example, the base station distributed unit may determine, based onthe at least one assistance parameter, whether to initiate/request theRRC release procedure for the wireless device (e.g., to the base stationcentral unit). The base station distributed unit may determine at leastone second information element of the assistance information. The atleast one second information element may indicate/request (e.g., to thebase station central unit) whether to initiate the RRC release procedurefor the wireless device.

In an example, the base station distributed unit may determine the atleast one second information element based on the at least oneassistance parameter received from the wireless device. In an example,if the at least one assistance parameter indicates one or more of norelease assistance information, no subsequent downlink datatransmission, no subsequent uplink data transmission, single subsequentdownlink data transmission, single subsequent uplink data transmission,and/or the like, the base station distributed unit may determine torequest/initiate the RRC release procedure for the wireless deviceand/or the at least one second information element may indicate/requestto perform the RRC release procedure for the wireless device. In anexample, if the first number of subsequent downlink data transmissionand/or the second number of subsequent uplink data transmission in theat least one assistance parameter is equal to or smaller than at leastone threshold value, the base station distributed unit may determine torequest/initiate the RRC release procedure for the wireless deviceand/or the at least one second information element may indicate/requestto perform the RRC release procedure for the wireless device. In anexample, the buffer status report in the at least one assistanceparameter indicates a data size that is equal to or smaller than athreshold size value, the base station distributed unit may determine torequest/initiate the RRC release procedure for the wireless deviceand/or the at least one second information element may indicate/requestto perform the RRC release procedure for the wireless device.

In an example, the base station distributed unit may determine the atleast one second information element based on the at least oneassistance parameter received from the wireless device. In an example,if the at least one assistance parameter indicates one or more of norelease assistance information, single subsequent downlink datatransmission, single subsequent uplink data transmission, and/or thelike, the base station distributed unit may determine torequest/initiate transition of the wireless device to the RRC connectedstate (e.g., not initiate the RRC release procedure for the wirelessdevice) and/or the at least one second information element mayindicate/request to transition the wireless device to the RRC connectedstate (e.g., to not initiate the RRC release procedure for the wirelessdevice). In an example, if the first number of subsequent downlink datatransmission and/or the second number of subsequent uplink datatransmission in the at least one assistance parameter is equal to orlarger than at least one threshold value, the base station distributedunit may determine to request/initiate transition of the wireless deviceto the RRC connected state (e.g., not initiate the RRC release procedurefor the wireless device) and/or the at least one second informationelement may indicate/request to transition the wireless device to theRRC connected state (e.g., to not initiate the RRC release procedure forthe wireless device). In an example, the buffer status report in the atleast one assistance parameter indicates a data size that is equal to orlarger than a threshold size value, the base station distributed unitmay determine to request/initiate transition of the wireless device tothe RRC connected state (e.g., not initiate the RRC release procedurefor the wireless device) and/or the at least one second informationelement may indicate/request to transition the wireless device to theRRC connected state (e.g., to not initiate the RRC release procedure forthe wireless device).

In an example, the base station distributed unit may determine the atleast one second information element further based on resource status ofthe base station distributed unit and/or the cell of the base stationdistributed unit. In an example, if the resource status (e.g., radioresource block usage ratio, radio resource overload status, hardwareoverload status, etc.) of the base station distributed unit and/or thecell is equal to or larger than a resource threshold value, the basestation distributed unit may determine to request/initiate the RRCrelease procedure for the wireless device and/or the at least one secondinformation element may indicate/request to perform the RRC releaseprocedure for the wireless device.

In an example, if the resource status (e.g., radio resource block usageratio, radio resource overload status, hardware overload status, etc.)of the base station distributed unit and/or the cell is equal to orsmaller than a resource threshold value, the base station distributedunit may determine to recommend/initiate transition of the wirelessdevice to the RRC connected state (e.g., not initiate the RRC releaseprocedure for the wireless device) and/or the at least one secondinformation element may indicate/recommend to transition the wirelessdevice to the RRC connected state (e.g., to not initiate the RRC releaseprocedure for the wireless device) or may indicate availabilityindication of transition the wireless device to the RRC connected state.

In an example, the base station distributed unit may send, to the basestation central unit (gNB-CU), at least one message comprising the RRCrequest message for the small data transmission and/or assistanceinformation for initiation of the RRC release procedure for the wirelessdevice. The base station central unit may receive, from the base stationdistributed unit, the at least one message comprising the RRC requestmessage from the wireless device for the small data transmission and/orthe assistance information. The assistance information may be based onthe at least one assistance parameter. The assistance information maycomprise the at least one first information element indicating whetherthe at least one subsequent data transmission is expected. Theassistance information may comprise the at least one second informationelement indicating/requesting/recommending whether to initiate the RRCrelease procedure for the wireless device (e.g., or whether totransition the wireless device to the RRC connected state).

In an example, the receiving by the base station central unit the atleast one message from the base station distributed unit may comprisereceiving the at least one message via the F1 interface. The at leastone message may comprise at least one of: an initial UL RRC messagetransfer message, an UL RRC message transfer message, a UE contextmodification/setup required message, a UE context setup/modificationmessage, a notify message, an access success message, and/or the like.

In an example, the at least one message may comprise at least one of: awireless device identifier (e.g., gNB-DU UE F1AP ID, gNB-CU UE F1AP ID,TMSI, S-TMSI, C-RNTI, PUR-RNTI, IMSI, etc.) of the wireless device, acell identifier (e.g., NR CGI, cell global identifier, physical cellidentifier, etc.) of the cell that the wireless device accesses for thesmall data transmission, an RRC container comprising the RRC requestmessage, a DU to CU RRC container comprising cell configurationparameters and/or SRB/DRB configuration parameters configured for thewireless device, a supplementary uplink (SUL) access indicationindicating whether the wireless device uses a supplementary uplink or anormal uplink to access the cell, a transaction identifier (e.g.,transaction ID), a RAN UE ID, a second RRC container (e.g.,RRC-Container-RRCSetupComplete, RRC-Container-RRCResumeComplete,RRC-Container-RRCRelease) comprising an RRC setup/resume completemessage and/or an RRC release message, an SRB identifier of an SRB(e.g., SRB1/2/3), a PLMN identifier (e.g., selected PLMN identifier),and/or the like.

In an example, the assistance information of the at least one messagemay comprise the buffer status report from the wireless device. Thebuffer status report may indicate size of data to transmit. Theassistance information of the at least one message may comprise aninformation element (e.g., SDT indication, EDT indication) indicatingthe small data transmission (e.g., MO-SDT, MO-EDT, MT-SDT, MT-EDT,etc.). The assistance information of the at least one message maycomprise the bearer identifier of the bearer (e.g., logical channel, QoSflow, PDU session) associated with the small data transmission, as shownin FIG. 29 . In an example, the assistance information of the at leastone message may comprise at least one of: the bearer identifier of thebearer, the logical channel identifier of the logical channel, thelogical channel group identifier of the logical channel group, the QoSflow identifier of the QoS flow, the session identifier of the PDUsession, and/or the like. The bearer, the logical channel, the logicalchannel group, the QoS flow, the PDU session may be configured for dataassociated with the small data transmission. Based on the beareridentifier (e.g., and/or the logical channel identifier, the logicalchannel group identifier, the QoS flow identifier, the sessionidentifier) of the assistance information, the base station central unitmay resume/establish/setup the bearer for the wireless device (e.g.,only the bearer among a plurality of suspended bearers of the wirelessdevice; only the logical channel/the logical channel group/the QoSflow/the PDU session among a plurality of logical channels, logicalchannel groups, QoS flows, and/or PDU sessions of the wireless device).For resuming/establishing the bearer (e.g., the logical channel, thelogical channel group, the QoS flow, the PDU session), the base stationcentral unit may perform a UE context setup/modification procedure forthe wireless device with the base station distributed unit. For the UEcontext setup/modification procedure, the base station central unit maysend, to the base station distributed unit, a context setup/modificationrequest message comprising the bearer identifier of the bearer (e.g.,and/or the logical channel identifier, the logical channel groupidentifier, the QoS flow identifier, the session identifier). The basestation central unit may receive, from the base station distributedunit, an acknowledge message indicating completion ofresuming/establishing the bearer (e.g., the logical channel, the logicalchannel group, the QoS flow, the PDU session).

In an example, the context setup/modification request message maycomprise at least one of: a wireless device identifier (e.g., gNB-DU UEF1AP ID, gNB-CU UE F1AP ID, TMSI, S-TMSI, C-RNTI, PUR-RNTI, IMSI, etc.)of the wireless device, a cause parameter, an RRC container, a CU to DURRC container comprising cell configuration parameters and/or SRB/DRBconfiguration parameters (e.g., QoS parameters, QoS flow identifier,S-NSSAI, network slice information, tunnel information, beareridentifier, etc.) configured for the wireless device, a transactionidentifier (e.g., transaction ID), a RAN UE ID, an SRB identifier of anSRB (e.g., SRB1/2/3), a PLMN identifier (e.g., selected PLMNidentifier), a candidate cell list to be cancelled for the wirelessdevice, an SpCell identifier of an SpCell for the wireless device, aserving cell identifier of a serving cell for the wireless device, DRXcycle information, a secondary cell identifier of a secondary cell forthe wireless device, and/or the like.

In an example, the base station central unit may receive and/or forwardthe uplink data and/or subsequent uplink or downlink data. In anexample, the base station central unit may receive, from the wirelessdevice and via the base station distributed unit, uplink data associatedwith the small data transmission. The base station central unit maytransmit the uplink data to a core network node (e.g., UPF, S-GW; if thebase station central unit is a central unit of an anchor base stationand/or an old base station of the wireless device) or a second basestation (e.g., an anchor base station and/or an old base station of thewireless device).

In an example, the base station central unit may receive at least onesubsequent downlink data associated with the small data transmissionfrom the core network node or the second base station. The base stationcentral unit may transmit the at least one subsequent downlink data tothe wireless device via the base station distributed unit. In anexample, the at least one subsequent downlink data may be response data(e.g., from a device communicating with the wireless device) for theuplink data. In an example, the base station central unit may receive,from the wireless device and via the base station distributed unit, atleast one subsequent uplink data associated with the small datatransmission. The base station central unit may transmit the at leastone subsequent uplink data to the core network node or the second basestation. In an example, the at least one subsequent uplink data may beresponse data (e.g., from a device communicating with the wirelessdevice) for the at least one subsequent downlink data

In an example, the base station central unit may receive/transmit theuplink data, the at least one subsequent uplink data, and/or the atleast one subsequent downlink data from/to the base station distributedunit via at least one tunnel (e.g., based on uplink/downlink tunnelidentifier) between the base station central unit and the base stationdistributed unit. The base station central unit may receive/transmit theuplink data, the at least one subsequent uplink data, and/or the atleast one subsequent downlink data from/to the core network node and/orthe second base station via at least one tunnel (e.g., based onuplink/downlink tunnel identifier) between the base station central unitand the core network node and/or between the base station central unitand the second base station.

In an example, the base station central unit may determine, based on theat least one message, whether to initiate the RRC release procedure forthe wireless device. In an example, based on the reception/transmissionof the uplink data, the at least one subsequent uplink data, and/or theat least one subsequent downlink data, the base station central unit maydetermine whether to initiate the RRC release procedure for the wirelessdevice. In an example, the determining whether to initiate the RRCrelease procedure for the wireless device (e.g., whether to transitionthe wireless device to an RRC connected state; whether to proceed an RRCconnection resume/setup procedure) may comprise determining based oncompletion of the small data transmission (e.g., based on completion oftransmission/reception of the uplink data, the at least one subsequentuplink data, and/or the at least one subsequent downlink data). In anexample, the determining whether to initiate the RRC release procedurefor the wireless device may comprise at least one of determining whetherto transition the wireless device to the RRC connected state and/ordetermining whether to proceed an RRC connection resume/setup procedurefor the wireless device. In an example, determining to initiate the RRCrelease procedure for the wireless device may comprise determining totransition the wireless device to an RRC inactive state or an RRC idlestate. In an example, determining to not initiate the RRC releaseprocedure for the wireless device may comprise determining to transitionthe wireless device to the RRC connected state and/or determining toproceed an RRC connection resume/setup procedure for the wireless device(e.g., by sending/transmitting an RRC resume message and/or an RRC setupmessage to the wireless device).

In an example, the determining whether to initiate the RRC releaseprocedure for the wireless device may comprise at least one of:determining to initiate/perform the RRC release procedure, based on theassistance information indicating that no subsequent downlink or uplinkdata transmission is expected; determining to initiate the RRC releaseprocedure, based on the assistance information indicating that a singlesubsequent downlink or uplink data transmission is expected; determiningto transition the wireless device to the RRC connected state, based onthe assistance information indicating that one or more subsequentdownlink or uplink data transmissions are expected; and/or the like.

In an example, the base station central unit may determine whether toinitiate the RRC release procedure for the wireless device based on theassistance information (e.g., the at least one first informationelement, the at least one second information element, the buffer statusreport, etc.) received from the base station distributed unit. In anexample, if the at least one first information element indicates one ormore of no release assistance information, no subsequent downlink datatransmission, no subsequent uplink data transmission, single subsequentdownlink data transmission, single subsequent uplink data transmission,and/or the like, the base station central unit may determine toinitiate/perform the RRC release procedure for the wireless deviceand/or to send/transmit the RRC release message to the wireless devicefor the RRC release procedure. In an example, if the first number ofsubsequent downlink data transmission and/or the second number ofsubsequent uplink data transmission in the at least one firstinformation element is equal to or smaller than at least one thresholdvalue, the base station central unit may determine to initiate/performthe RRC release procedure for the wireless device and/or tosend/transmit the RRC release message to the wireless device for the RRCrelease procedure. In an example, the buffer status report in theassistance information indicates a data size that is equal to or smallerthan a threshold size value, the base station central unit may determineto initiate/perform the RRC release procedure for the wireless deviceand/or to send/transmit the RRC release message to the wireless devicefor the RRC release procedure. In an example, if the at least one secondinformation element indicates/requests to perform the RRC releaseprocedure for the wireless device (e.g., and/or not transition thewireless device to an RRC connected state), the base station centralunit may determine to initiate/perform the RRC release procedure for thewireless device and/or to send/transmit the RRC release message to thewireless device for the RRC release procedure. In an example, the atleast one second information element indicates that transitioning thewireless device to the RRC connected state is unavailable, the basestation central unit may determine to initiate/perform the RRC releaseprocedure for the wireless device and/or to send/transmit the RRCrelease message to the wireless device for the RRC release procedure.

In an example, the base station central unit may determine whether toinitiate the RRC release procedure for the wireless device based on theassistance information (e.g., the at least one first informationelement, the at least one second information element, the buffer statusreport, etc.) received from the base station distributed unit. In anexample, if the at least one first information element indicates one ormore of no release assistance information, single subsequent downlinkdata transmission, single subsequent uplink data transmission, and/orthe like, the base station central unit may determine to transition thewireless device to the RRC connected state (e.g., not initiate the RRCrelease procedure for the wireless device) and/or to send/transmit theRRC resume/setup message to the wireless device for transition of thewireless device to the RRC connected state. In an example, if the firstnumber of subsequent downlink data transmission and/or the second numberof subsequent uplink data transmission in the at least one firstinformation element is equal to or larger than at least one thresholdvalue, the base station central unit may determine to transition thewireless device to the RRC connected state (e.g., not initiate the RRCrelease procedure for the wireless device) and/or to send/transmit theRRC resume/setup message to the wireless device for transition of thewireless device to the RRC connected state. In an example, the bufferstatus report in the assistance information indicates a data size thatis equal to or larger than a threshold size value, the base stationcentral unit may determine to transition the wireless device to the RRCconnected state (e.g., not initiate the RRC release procedure for thewireless device) and/or to send/transmit the RRC resume/setup message tothe wireless device for transition of the wireless device to the RRCconnected state. In an example, if the at least one second informationelement indicates/requests to not perform the RRC release procedure forthe wireless device (e.g., and/or to transition the wireless device toan RRC connected state), the base station central unit may determine totransition the wireless device to the RRC connected state (e.g., notinitiate the RRC release procedure for the wireless device) and/or tosend/transmit the RRC resume/setup message to the wireless device fortransition of the wireless device to the RRC connected state. In anexample, the at least one second information element indicates thattransitioning the wireless device to the RRC connected state isavailable, the base station central unit may determine to transition thewireless device to the RRC connected state (e.g., not initiate the RRCrelease procedure for the wireless device) and/or to send/transmit theRRC resume/setup message to the wireless device for transition of thewireless device to the RRC connected state.

In an example, the base station central unit may determine whether toinitiate the RRC release procedure for the wireless device further basedon resource status of the base station central/distributed unit and/orthe cell of the base station associated with the base station centralunit. In an example, if the resource status (e.g., radio resource blockusage ratio, radio resource overload status, hardware overload status,etc.) of the base station central/distributed unit and/or the cell ofthe base station associated with the base station central unit is equalto or larger than a resource threshold value, the base station centralunit may determine to initiate/perform the RRC release procedure for thewireless device and/or to send/transmit the RRC release message to thewireless device for the RRC release procedure.

In an example, if the resource status (e.g., radio resource block usageratio, radio resource overload status, hardware overload status, etc.)of the base station central/distributed unit and/or the cell of the basestation associated with the base station central unit is equal to orsmaller than a resource threshold value, the base station central unitmay determine to transition the wireless device to the RRC connectedstate (e.g., not initiate the RRC release procedure for the wirelessdevice) and/or to send/transmit the RRC resume/setup message to thewireless device for transition of the wireless device to the RRCconnected state.

In an example, based on the determining whether to initiate the RRCrelease procedure, the base station central unit may send, to thewireless device, an RRC release message for the RRC release procedure oran RRC message for the wireless device to transition to an RRC connectedstate. The base station central unit may send/transmit, to the basestation distributed unit, a context message comprising the RRC releasemessage for the RRC release procedure or the RRC message for thewireless device to transition to the RRC connected state. The basestation distributed unit may receive, from the base station centralunit, the context message comprising the RRC release message or the RRCmessage for the wireless device. In an example, if the base stationcentral unit determines to initiate the RRC release procedure (e.g., tonot transition the wireless device to the RRC connected state), the basestation central unit may transmit/send the RRC release message to thewireless device via the context message and/or via the base stationdistributed unit. In an example, if the base station central unitdetermines to not initiate the RRC release procedure (e.g., totransition the wireless device to the RRC connected state), the basestation central unit may transmit/send the RRC message (e.g., the RRCresume message, the RRC setup message, etc.) to the wireless device viathe context message and/or via the base station distributed unit. In anexample, the RRC message may comprise at least one of: an RRC resumemessage, an RRC setup message, and/or the like. The RRC release messagemay comprise at least one of: an RRC connection release message, an RRCearly data complete message, and/or the like. The RRC release messagemay comprise configuration parameters for suspension of an RRCconnection. In an example, the sending the RRC release message or theRRC message by the base station central unit may comprise sending theRRC release message or the RRC message to the wireless device via thebase station distributed unit.

In an example, the sending/transmitting by the base station central unitthe context message to the base station distributed unit may comprisesending/transmitting the context message via the F1 interface. In anexample, the context message may comprise at least one of: a UE contextrelease command message, an DL RRC message transfer message, a UEcontext modification/setup request message, a UE contextsetup/modification complete message, a notify message, an access successmessage, and/or the like.

In an example, the context message may comprise at least one of: awireless device identifier (e.g., gNB-DU UE F1AP ID, gNB-CU UE F1AP ID,TMSI, S-TMSI, C-RNTI, PUR-RNTI, IMSI, etc.) of the wireless device, acause parameter (e.g., cause of performing the RRC release procedure),an RRC container comprising the RRC release message or the RRC message(e.g., the RRC setup/resume message), a CU to DU RRC containercomprising cell configuration parameters and/or SRB/DRB configurationparameters (e.g., QoS parameters, QoS flow identifier, S-NSSAI, networkslice information, tunnel information, bearer identifier, etc.)configured for the wireless device, a transaction identifier (e.g.,transaction ID), a RAN UE ID, a second RRC container (e.g.,RRC-Container-RRCSetupComplete, RRC-Container-RRCResumeComplete,RRC-Container-RRCRelease) comprising an RRC setup/resume completemessage and/or an RRC release message, an SRB identifier of an SRB(e.g., SRB1/2/3), a PLMN identifier (e.g., selected PLMN identifier), acandidate cell list to be cancelled for the wireless device, an SpCellidentifier of an SpCell for the wireless device, a serving cellidentifier of a serving cell for the wireless device, DRX cycleinformation, a secondary cell identifier of a secondary cell for thewireless device, and/or the like. In an example, if the context messagecomprises the RRC release message for the RRC release procedure of thewireless device, the context message may be a UE context release commandmessage. In an example, if the context message comprises the RRC message(e.g., the RRC setup/resume message) to transition the wireless deviceto the RRC connected state, the context message may be a UE contextmodification/setup request message, a UE context modification/setupconfirm message, DL RRC message transfer message, and/or the like.

In an example, the RRC release message may comprise a list of at leastone bearer (e.g., SRB, DRB) that is allowed to use procedure of thesmall data transmission (e.g., the early data transmission). Based onthe list of the at least one bearer, the wireless device may perform thesmall data transmission if the wireless device has data associated withthe at least one bearer when the wireless device is in the RRC inactivestate or the RRC idle state.

In an example, the base station distributed unit may transmit/forward,to the wireless device, the RRC release message or the RRC message. Inan example, the wireless device may be in the RRC idle state or the RRCinactive state based on receiving the RRC release message from the basestation distributed unit and/or the base station central unit. In anexample, the wireless device may send/transmit an RRC complete messagein response to receiving the RRC message from the base stationdistributed unit and/or the base station central unit. The wirelessdevice may transition to the RRC connected state (e.g.,establish/resume/setup the RRC connection with the base station) basedon the RRC message from the base station distributed unit and/or thebase station central unit. The RRC complete message may comprise atleast one of an RRC setup complete message, an RRC resume completemessage, and/or the like.

In an example, the base station distributed unit may transmit/send, tothe wireless device, the initial downlink data and/or the at least onesubsequent downlink data by multiplexing and/or concatenating theinitial downlink data and/or the at least one subsequent downlink datawith the RRC release message or the RRC message.

In an example, as show in FIG. 30 , a base station central unit mayreceive, from a base station distributed unit, at least one messagecomprising a radio resource control (RRC) request message from awireless device for a small data transmission (e.g., early datatransmission) and/or assistance information for initiation of an RRCrelease procedure for the wireless device. The base station central unitmay determine, based on the at least one message, whether to initiatethe RRC release procedure for the wireless device. Based on thedetermining, the base station central unit may send, to the wirelessdevice, an RRC release message for the RRC release procedure or an RRCmessage for the wireless device to transition to an RRC connected state.

In an example, the assistance information may comprise at least onefirst information element indicating whether at least one subsequentdata transmission is expected. In an example, the assistance informationmay comprise at least one second information elementindicating/requesting whether to initiate the RRC release procedure forthe wireless device. The at least one subsequent data transmission maybe associated with the small data transmission. The at least onesubsequent data transmission may comprise at least one of at least onesubsequent uplink data transmission, at least one subsequent downlinkdata transmission, and/or the like. In an example, the at least onefirst information element may comprise at least one of: a parameterindicating no release assistance information, a parameter indicating nosubsequent downlink data transmission is expected, a parameterindicating no subsequent uplink data transmission is expected, aparameter indicating a single subsequent downlink data transmission isexpected, a parameter indicating a single subsequent uplink datatransmission is expected; a first number of subsequent downlink datatransmission expected, a second number of subsequent uplink datatransmission expected, and/or the like.

In an example, the assistance information may comprise a buffer statusreport from the wireless device. The buffer status report may indicatesize of data to transmit. The assistance information may comprise aninformation element (e.g., SDT indication) indicating the small datatransmission. The assistance information may comprise a beareridentifier of a bearer (e.g., logical channel, QoS flow, PDU session)associated with the small data transmission. Based on the beareridentifier of the assistance information, the base station central unitmay resume/establish/setup the bearer for the wireless device (e.g.,only the bearer among a plurality of suspended bearers of the wirelessdevice). For resuming/establishing the bearer, the base station centralunit may send, to the base station distributed unit, a contextsetup/modification request message comprising the bearer identifier ofthe bearer, and/or the base station central unit may receive, from thebase station distributed unit, an acknowledge message indicatingcompletion of resuming/establishing the bearer.

In an example, the small data transmission may comprise transmission ofat least one of: an initial uplink data, an initial downlink data, atleast one subsequent uplink data, at least one subsequent downlink data,and/or the like.

In an example, the determining whether to initiate the RRC releaseprocedure for the wireless device (e.g., whether to transition thewireless device to an RRC connected state; whether to proceed an RRCconnection resume/setup procedure) may comprise determining based oncompletion of the small data transmission. The determining whether toinitiate the RRC release procedure for the wireless device may compriseat least one of: determining to initiate the RRC release procedure,based on the assistance information indicating that no subsequentdownlink or uplink data transmission is expected; determining toinitiate the RRC release procedure, based on the assistance informationindicating that a single subsequent downlink or uplink data transmissionis expected; determining to transition the wireless device to the RRCconnected state, based on the assistance information indicating that oneor more subsequent downlink or uplink data transmissions are expected;and/or the like.

In an example, the base station distributed unit may receive, from thewireless device, at least one of: the RRC request message for the smalldata transmission, uplink data associated with the small datatransmission, at least one assistance parameter (e.g., releaseassistance information, RAI) indicating whether at least one subsequentdata transmission is expected, and/or the like. The receiving the atleast one assistance parameter may comprise receiving the at least oneassistance parameter via at least one of: at least one medium accesscontrol element (MAC CE), a physical uplink channel (e.g., PUSCH, PUCCH,uplink control information, UCI), at least one radio link control (RLC)packet header, and/or the like. In an example, the at least oneassistance parameter may comprise at least one of: a parameterindicating no release assistance information; a parameter indicating nosubsequent downlink data transmission is expected; a parameterindicating no subsequent uplink data transmission is expected; aparameter indicating a single subsequent downlink data transmission isexpected; a parameter indicating a single subsequent uplink datatransmission is expected; a first number of subsequent downlink datatransmission expected; a second number of subsequent uplink datatransmission expected; a buffer status report indicating size of data totransmit; and/or the like.

In an example, the base station distributed unit may construct, based onthe at least one assistance parameter, at least one first informationelement of the assistance information. The at least one firstinformation element may indicate whether at least one subsequent datatransmission is expected. The at least one first information element maybe an information element of an F1 message. In an example, the basestation distributed unit may determine, based on the at least oneassistance parameter, whether to initiate the RRC release procedure forthe wireless device. The base station distributed unit may transmit, tothe base station central unit and based on the determining, at least onesecond information element via the assistance information. The at leastone second information element may indicate/request whether to initiatethe RRC release procedure for the wireless device.

In an example, the receiving by the base station distributed unit theRRC request message may comprise receiving the RRC request message basedon a random access process of the wireless device. The receiving by thebase station distributed unit the RRC request message may comprisereceiving the RRC request message via at least one preconfigured uplinkresource (PUR).

In an example, the RRC request message may comprise at least one of: anRRC early data transmission request message, an RRC resume requestmessage, an RRC setup request message, and/or the like. The RRC messagemay comprise at least one of: an RRC resume message, an RRC setupmessage, and/or the like. The RRC release message may compriseconfiguration parameters for suspension of an RRC connection.

In an example, the base station central unit may receive, from thewireless device and via the base station distributed unit, uplink dataassociated with the small data transmission. The base station centralunit may transmit the uplink data to a core network node (e.g., UPF,S-GW; if the base station central unit is a central unit of an anchorbase station and/or an old base station of the wireless device) or asecond base station (e.g., an anchor base station and/or an old basestation of the wireless device). In an example, the base station centralunit may receive at least one subsequent downlink data associated withthe small data transmission from the core network node or the secondbase station. The base station central unit may transmit the at leastone subsequent downlink data to the wireless device via the base stationdistributed unit. In an example, the base station central unit mayreceive, from the wireless device and via the base station distributedunit, at least one subsequent uplink data associated with the small datatransmission. The base station central unit may transmit the at leastone subsequent uplink data to the core network node or the second basestation.

In an example, the sending the RRC release message or the RRC messagemay comprise sending the RRC release message or the RRC message to thewireless device via the base station distributed unit.

In an example, the base station distributed unit may receive, from thewireless device, at least one random access preamble. The base stationdistributed unit may transmit, to the wireless device, at least onerandom access response for the at least one random access preamble. TheRRC request message may be based on the at least one random accessresponse. The at least one random access preamble may be configured forthe small data transmission. In an example, the base station distributedunit may receive, from the base station central unit, a configurationmessage indicating the at least one random access preamble for the smalldata transmission. The base station distributed unit maytransmit/broadcast, to a plurality of wireless devices comprising thewireless device, a system information block indicating the at least onerandom access preamble for the small data transmission. The receiving bythe base station distributed unit the at least one random accesspreamble may be based on the system information block. The wirelessdevice may transmit the at least one random access preamble based on thesystem information block.

In an example, as show in FIG. 31 , a base station distributed unit mayreceive, from a wireless device, an RRC request message for a small datatransmission, uplink data, and/or at least one assistance parameterindicating whether at least one subsequent data transmission isexpected. The base station distributed unit may send, to a base stationcentral unit, at least one message comprising the RRC request messagefor the small data transmission and/or assistance information forinitiation of an RRC release procedure for the wireless device. Theassistance information may be based on the at least one assistanceparameter. The base station distributed unit may receive, from the basestation central unit, a context message based on the at least onemessage. The context message may comprise at least one of: an RRCrelease message for the RRC release procedure of the wireless device oran RRC message for the wireless device to transition to an RRC connectedstate.

In an example, the assistance information may comprise at least one of:at least one first information element indicating whether at least onesubsequent data transmission is expected; at least one secondinformation element indicating/requesting whether to initiate an RRCrelease procedure for the wireless device; and/or the like. The basestation distributed unit may transmit/forward, to the wireless device,the RRC release message or the RRC message.

In an example, as show in FIG. 31 , a base station distributed unit mayreceive, from a wireless device, an RRC request message for a small datatransmission, uplink data, and/or at least one assistance parameterindicating whether at least one subsequent data transmission isexpected. The base station distributed unit may send/transmit, to a basestation central unit, at least one message comprising the RRC requestmessage for the small data transmission and/or at least one firstinformation element indicating whether the at least one subsequent datatransmission is expected. The base station distributed unit may receive,from the base station central unit, a context message based on the atleast one message. The context message may comprise at least one of: anRRC release message for an RRC release procedure of the wireless deviceor an RRC message for the wireless device to transition to an RRCconnected state.

In an example, the receiving the at least one assistance parameter maycomprise receiving the at least one assistance parameter via at leastone of: a medium access control control element (MAC CE), a physicallayer control information (e.g., PUSCH, PUCCH, uplink controlinformation, UCI), at least one radio link control (RLC) packet header,and/or the like. The base station distributed unit may construct the atleast one first information element based on the at least one assistanceparameter. The at least one first information element may be aninformation element of a F1 message.

In an example, as show in FIG. 31 , a base station distributed unit mayreceive, from a wireless device, an RRC request message for a small datatransmission, uplink data, and/or at least one assistance parameterindicating whether at least one subsequent data transmission isexpected. The base station distributed unit may determine, based on theat least one assistance parameter, whether to initiate an RRC releaseprocedure for the wireless device. The base station distributed unit maysend, to a base station central unit, at least one message comprisingthe RRC request message for the small data transmission and/or at leastone second information element indicating/requesting whether to initiatethe RRC release procedure for the wireless device. The base stationdistributed unit may receive, from the base station central unit, acontext message based on the at least one message. The context messagemay comprise at least one of: an RRC release message for the RRC releaseprocedure of the wireless device or an RRC message for the wirelessdevice to transition to an RRC connected state.

In an example, as show in FIG. 30 , a base station central unit mayreceive, from a base station distributed unit, at least one messagecomprising an RRC request message from a wireless device for a smalldata transmission and/or at least one first information elementindicating whether at least one subsequent data transmission isexpected. The base station central unit may determine, based on themessage, whether to initiate a RRC release procedure for the wirelessdevice. Based on the determining, the base station central unit maysend, to the wireless device, an RRC release message for the RRC releaseprocedure or an RRC message for wireless device to transition to an RRCconnected state.

In an example, as show in FIG. 30 , a base station central unit mayreceive, from a base station distributed unit, at least one messagecomprising a RRC request message from a wireless device for a small datatransmission and/or at least one second information elementindicating/requesting whether to initiate an RRC release procedure forthe wireless device. The base station central unit may determine, basedon the at least one message, whether to initiate the RRC releaseprocedure for the wireless device. Based on the determining, the basestation central unit may send, to the wireless device, an RRC releasemessage for the RRC release procedure or an RRC message for wirelessdevice to transition to an RRC connected state.

The invention claimed is:
 1. A method comprising: receiving, by a base station central unit from a base station distributed unit, assistance information indicating whether subsequent data is expected for a small data transmission (SDT) procedure of a wireless device; and transmitting a radio resource control (RRC) release message to the wireless device based on the assistance information.
 2. The method of claim 1, wherein the transmitting the RRC release message is based on determining that the SDT procedure is complete.
 3. The method of claim 1, further comprising determining to transmit the RRC release message based on the assistance information indicating that no subsequent data is expected.
 4. The method of claim 1, further comprising determining that the SDT procedure is complete based on the assistance information indicating that no subsequent data is expected.
 5. The method of claim 4, wherein determining that the SDT procedure is complete based on: the assistance information indicating that a single transmission or reception of subsequent data is expected; and the single transmission or reception of subsequent data being received or transmitted.
 6. The method of claim 1, further comprising receiving, by the base station central unit from the wireless device via the base station distributed unit, uplink data associated with the SDT procedure.
 7. The method of claim 1, wherein the assistance information is based on at least one assistance parameter received from the wireless device at the base station distributed unit via at least one medium access control (MAC) control element (CE).
 8. The method of claim 1, further comprising determining to send the RRC release message based on: the assistance information indicating that a plurality of transmissions or receptions of subsequent data are expected; and the plurality of transmissions or receptions of subsequent data being received or transmitted.
 9. The method of claim 1, wherein the transmitting the RRC release message is based on a buffer status report of the wireless device.
 10. The method of claim 9, wherein the buffer status report indicates that an amount of the subsequent data is below a threshold data amount.
 11. A base station central unit comprising one or more processors and memory storing instructions that, when executed by the one or more processors, cause the base station central unit to perform operations comprising: receiving, from a base station distributed unit, assistance information indicating whether subsequent data is expected for a small data transmission (SDT) procedure of a wireless device; and transmitting a radio resource control (RRC) release message to the wireless device based on the assistance information.
 12. The base station central unit of claim 11, wherein the transmitting the RRC release message is based on determining that the SDT procedure is complete.
 13. The base station central unit of claim 11, further comprising determining to transmit the RRC release message based on the assistance information indicating that no subsequent data is expected.
 14. The base station central unit of claim 11, further comprising determining that the SDT procedure is complete based on the assistance information indicating that no subsequent data is expected.
 15. The base station central unit of claim 14, wherein determining that the SDT procedure is complete based on: the assistance information indicating that a single transmission or reception of subsequent data is expected; and the single transmission or reception of subsequent data being received or transmitted.
 16. The base station central unit of claim 11, further comprising receiving, by the base station central unit from the wireless device via the base station distributed unit, uplink data associated with the SDT procedure.
 17. The base station central unit of claim 11, wherein the assistance information is based on at least one assistance parameter received from the wireless device at the base station distributed unit via at least one medium access control (MAC) control element (CE).
 18. The base station central unit of claim 11, further comprising determining to send the RRC release message based on: the assistance information indicating that a plurality of transmissions or receptions of subsequent data are expected; and the plurality of transmissions or receptions of subsequent data being received or transmitted.
 19. The base station central unit of claim 11, wherein the transmitting the RRC release message is based on a buffer status report of the wireless device.
 20. A system, comprising: a base station distributed unit comprising: one or more processors and memory storing instructions that, when executed by the one or more processors, cause the base station distributed unit to perform operations comprising: receiving, from a wireless device, one or more parameters indicating subsequent data for a small data transmission (SDT) procedure of the wireless device; transmitting, to a base station central unit, assistance information indicating whether subsequent data is expected for the SDT procedure; receiving, from the base station central unit, an radio resource control (RRC) release message; and transmitting, to the wireless device, the RRC release message; and the base station central unit, wherein the base station central unit comprises: one or more processors and memory storing instructions that, when executed by the one or more processors, cause the base station central unit to perform operations comprising: receiving, from the base station distributed unit, the assistance information; and transmitting the RRC release message to the wireless device based on the assistance information. 